Data storage system and method for calibrating same

ABSTRACT

Disclosed herein are aspects of optical tape technology, tape manufacturing, and tape usage. Methods and systems of tape technology disclose optical tape media including: configurations, formulations, markings, and structure; optical tape manufacturing methods, systems, and apparatus methods and systems including: curing processes, coating methods, embossing, drums, testing, tracking alignment stamper strip; optical tape methods and systems including: pick up head adapted for the disclosed optical tape; and optical tape uses including optical storage media devices for multimedia applications

BACKGROUND

An optical pick-up unit may not be able to maintain focus on certaindefects of an optical media.

SUMMARY

Disclosed herein are aspects of optical tape technology, tapemanufacturing, and tape usage. Methods and systems of tape technologydisclose optical tape media including: configurations, formulations,markings, and structure; optical tape manufacturing methods, systems,and apparatus methods and systems including: curing processes, coatingmethods, embossing, drums, testing, tracking alignment stamper strip;optical tape methods and systems including: pick up head adapted for thedisclosed optical tape; and optical tape uses including optical storagemedia devices for multimedia applications.

A data storage system may include an optical media having a defect and aplurality of tracks on each side of the defect exhibiting (i) fields ofmodulated wobble indicative of defect location information next to thedefect and (ii) fields of modulated wobble indicative of data. The datastorage system may also include an optical pick-up unit configured toread the fields of modulated wobble, and at least one controlleroperatively arranged with the pick-up unit. The at least one controllermay be configured to, in response to the pick-up unit detecting defectlocation information on one side of the defect, command movement of themedia in a first direction such that the pick-up unit is positionedadjacent to the fields of modulated wobble indicative of data on theother side of the defect.

All documents mentioned herein are hereby incorporated in their entiretyby reference.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of an optical media including an optical servomark and data tracks.

FIG. 2 is a perspective view of an optical media processing system.

FIG. 3 shows an embodiment of a first surface incident (air-incident)WORM media layers.

FIG. 4 shows an embodiment of a first surface incident (air-incident)rewritable media layers.

FIG. 5 shows an embodiment of a second surface incident(basefilm-incident) WORM media layers.

FIG. 6 shows an embodiment of a second surface incident(basefilm-incident) rewritable media layers.

FIGS. 7A and 7B are cut away views representative of an optical mediastack-up of a possible embodiment of the invention.

FIGS. 8A and 8B includes images of optical media showing a dark spotwith surrounding a bright ring.

FIG. 9 is an image of write bright and write dark media.

FIG. 10 is a signal comparison of write bright and write dark.

FIG. 11 is a block diagram of a possible embodiment of the invention.

FIG. 12 is a schematic diagram of a possible embodiment of the sectionsof optical media of the invention.

FIG. 13 is a time lapse diagram showing a sequence of possible operatingmodes and the possible relative motion of the read/servo sense element.

FIG. 14 shows an embodiment of the sinusoidal signal that representsaddress and synchronization information.

FIG. 15 shows a block diagram embodiment of the servo system demodulatorand decoder.

FIG. 16 shows an embodiment of the various signal outputs of the servosystem demodulator show in FIG. 15.

FIG. 17 shows an embodiment of different optical marks and read backsignals.

FIG. 18 shows an embodiment of the servo dark marks embedded into thedata field white marks on the same optical media tracks.

FIG. 19 shows an embodiment of the read back signal resulting from theservo field and data fields using dark and white marks on the opticaltape media.

FIG. 20 is a graphical representation of the layer type and stack-up ofa possible embodiment of the invention.

FIG. 21 is an oscilloscope display of certain signal activity while anadapted embodiment of FIG. 20 is being tested.

FIG. 22 is a graph showing the reflection sensitivity in a 3-layer WORMmedia at 532 nm wavelength incident light.

FIG. 23 is an extension of FIG. 22 showing reflectivity of media withlayer thickness approx ten times that used to generate the graph of FIG.22.

FIG. 24 is a graph showing the reflection sensitivity in a DVD media at680 nm wavelength incident light.

FIG. 25 is a graph showing the reflection sensitivity of a media.

FIG. 26 is a graph showing the reflection sensitivity of a LOTS media.

FIG. 27 is a graph showing the reflection sensitivity of a DVD mediaversus wavelength of incident light.

FIG. 28 is a graph showing crossing reflection sensitivity curves for amedia.

FIG. 29 shows an embodiment of a direct read after write (DRAW) opticaltape pickup.

FIG. 30 shows an embodiment of a direct read after write (DRAW) opticaltape pickup.

FIG. 31 shows an embodiment of a holographic optical element used forthe secondary beam in an optical tape system.

FIG. 32 shows an embodiment of a holographic optical element used forthe DRAW beam in an optical tape system.

FIG. 33 shows an embodiment of an orientation of a first laser diode anda second laser diode in an optical tape system.

FIG. 34 shows an embodiment of a DRAW optical tape pickup head with thefirst and second electro-optic integrated circuit integrated into onechip.

FIG. 35 shows an embodiment of a compact DRAW optical tape pickup head.

FIG. 36 shows an embodiment of a compact DRAW optical tape pickup head.

FIG. 37 shows an embodiment of an optical tracking system adapted foroptical tape and an embodiment of the invention with the unit moving totrack the optical tape.

FIG. 38 shows an embodiment of an optical vignetting effect.

FIG. 39 shows an embodiment of an integrated optical tape pickup headdesign.

FIG. 40 shows an embodiment of an integrated optical tape pickup headwith the addition of a direct read after write feature incorporated.

FIG. 41 shows an embodiment of a re-orientation of the optical headtransport facility at the tape position extremes.

FIG. 42 illustrates an embodiment of an optical tape pick up headtransport facility showing a plurality of head channels with independentfocus and track control.

FIG. 43 shows an embodiment of a re-orientation of the head transportfacility at tape position extremes.

FIG. 44 shows an embodiment of a transducer assembly reading previouslywritten data and providing information to the writer for the nextinformation to write.

FIG. 45 shows a high level embodiment of a signal modulator and signaldemodulator.

FIG. 46 shows an embodiment of a signal demodulator.

FIG. 47 shows an embodiment of the lateral tape movement (LTM) andresidual motion (RM) of each individual optical head.

FIG. 48 shows an embodiment of the servo track signal decoding.

FIG. 49 shows an embodiment of the sync bit and address bits of theservo signal.

FIG. 50 shows an embodiment of a servo system demodulator/decoder.

FIG. 51 is a flowchart of a possible embodiment of the shim producingprocess.

FIG. 52 is a side and top view of a possible embodiment of the planarassembly of the embossing drum.

FIG. 53 is an isometric view of a possible embodiment of a roller shaft.

FIG. 54 is side view of a possible embodiment of a roller guide assemblyof the invention mounted on the roller shaft of FIG. 53.

FIG. 55 is a side view of a possible embodiment of the tape supportapparatus of the invention.

FIG. 56 is a top view of the possible embodiment of FIG. 55.

FIG. 57 is a cutaway plan view of a possible embodiment of the guideroller of the invention.

FIG. 58A is a profile of a typically shaped mechanical drum forembossing a servo track on media.

FIG. 58B is a perspective view of an embodiment of the adjustment zoneof the invention on a mechanical drum.

FIG. 59 is a plan view of the adjustment zone and wobble cyclerelationship.

FIG. 60 is a perspective view of a possible embodiment of the tape mediaposition and planarizing support apparatus of the invention.

FIG. 61 is an end view of the embodiment of FIG. 60 in use with tapemedia and a media head.

FIG. 62 is a perspective view of another possible embodiment of theinvention.

FIG. 63 shows an embodiment of a single side of reel with the massreducing openings.

FIG. 64 shows an embodiment of the reel assembly.

FIG. 65 shows an embodiment of a stamper shim configuration forsubmicron embossing.

FIG. 66 shows an embodiment of a cross section of a stamper shim and afine alignment arrangement using a differential screw.

FIG. 67 shows an embodiment of an automated alignment using a closedloop system incorporating a piezoelectric transducer, a pickup head, andprocess electronics.

FIG. 68 is a perspective view of a possible embodiment of the opticaltape media tester of the invention.

FIG. 69 is a front view of a possible embodiment of the adapted opticaltape drive and optical media tester for testing optical tape media.

FIG. 70 is a side view of a possible embodiment of the invention showingan embossing drum prior to shim assembly.

FIG. 71 is a cut away end view of the possible embodiment of FIG. 1,with shims assembled.

FIG. 72 is an end view of a possible embodiment of the aligned seameddrum of the invention in use.

FIG. 73 depicts a process for improved performance of multilayer opticalmedia tape.

FIG. 74 depicts a cut away view of a possible embodiment of an opticaltape of the invention.

FIG. 75 shows a side view of the simplified coating path of the priorart.

FIG. 76 shows a top view of the embodiment of FIG. 75.

FIG. 77 shows a schematic illustrating the effects of non-uniform sourcedistributions on the coating uniformity as viewed from the direction ofsubstrate motion.

FIG. 78 shows a schematic illustrating the effects of non-uniform sourcedistributions on the substrate as viewed normal to the plane of thesubstrate at the deposition zone.

FIG. 79 shows a schematic drawing of one embodiment of the presentdisclosure, showing the tape path through the vacuum deposition zone.

FIG. 80 shows a schematic representation of the effects of multiplepasses through the coating zone by the method shown in FIG. 79.

FIG. 81 shows another embodiment of FIG. 79 in which individual idlerrolls are used to guide the tape.

FIG. 82 shows a schematic drawing for one embodiment of the presentprocess whereby excess overcoated material can be removed.

FIG. 83 shows a schematic drawing for one embodiment of the presentprocess for single-pass dual-sided coating.

FIG. 84 shows various embodiments of optical storage media.

FIG. 85 shows an embodiment of the optical recording media of FIG. 1integrated with a personal computer, and a detail of a subset of theembodiment.

FIG. 86 shows the optical recording media of FIG. 84 in a stand-aloneembodiment.

FIG. 87 shows the optical recording media of FIG. 1 in a cameraembodiment.

DETAILED DESCRIPTION

Optical tape technology, manufacturing, and application may be highlyinterconnected to achieve cost, performance, density, and other goalsrequired to deliver a commercially viable solution. A goal such as lowmanufacturing cost while also manufacturing reliable, high qualityoptical tape may require substantial innovation in manufacturingtechnology methods and systems. To produce optical tape that supportshigh density storage and high performance may require substantialinnovation in tape technology as well as manufacturing methods andsystems. Therefore, the methods and systems of manufacturing the opticaltape herein disclosed may be used to make the optical tape hereindisclosed, and the methods and systems of optical tape usage hereindisclosed may be used to utilize the optical tape herein disclosed.

Disclosed herein are aspects of optical tape technology, tapemanufacturing, and tape usage. Methods and systems of tape technologydisclose optical tape media including: configurations, formulations,markings, and structure; optical tape manufacturing methods, systems,and apparatus methods and systems including: curing processes, coatingmethods, embossing, drums, testing, tracking alignment stamper strip;optical tape methods and systems including: pick up head adapted for thedisclosed optical tape; and optical tape uses including optical storagemedia devices for multimedia applications.

An optical servo mark on an optical tape media, generated using a methodthat results in the optical servo mark being distinguishable from datamarks on the optical tape media, as described herein may be used in anoptical data storage tape drive.

Referring to FIG. 1, optical servo mark 110 may be a repetitive,substantially sinusoidal (or sow tooth) pattern spanning a height 120equal to or greater than a band of optical tracks 130. Servo mark 110may be optically distinguishable from data marks 140. A method formaking servo mark 110 optically distinguishable includes making servomark 110 much wider than data marks 140.

Optical servo mark 110 can be included on optical media by using one ormore optical heads (not shown) to mark the optical media. The processfor marking the optical media may include one or more of Phase Changing,Burning, or Grooving. The process may include using either an opticalservo track writing device, or an optical storage media drive. Methodsof generating optical servo mark 110 includes controlling the one ormore optical heads with a signal generator set to a frequency thatgenerates optical servo mark 110 in sinusoidal pattern as the opticalmedia moves under the one or more optical heads with a constant linearspeed. The frequency of the signal generator may be chosen such that itwould meet the sampling requirement of a servo tracking system of a tapedrive system on which the optical media would be used.

The one or more optical heads may each be dedicated to the band oftracks 130 on the optical media, each optical head having its ownactuator for the purpose of tracking and focusing within band 130. Therange of motion of each head may overlap bands of adjacent opticalheads.

Once the optical media may be completely marked, an optical head readingalong data track 140 will detect servo mark 110 as a pattern of readpulses 150 as the marked media passes by the optical head. Pulse readpattern 150 has a frequency 160 defined by the servo mark 110 patternand the speed of the tape as it moves by the optical head.

Pulse read pattern 150 also has a duty cycle 170 which may beproportional to the position of the head relative to the edge of theband dedicated to that head. Frequency 160 of the pulse read pattern 150may be substantially the same for all head positions across the band oftracks. Duty cycle 170, calculated by the equation (Td1/Tf) % may bedifferent for each track as shown by read pulse patterns 111 and 113.

Pulse read pattern 150 may be used to position the optical head in asubstantially stationary manner over any desired track. A phase lockloop of a predetermined frequency may be used to qualify pulse readpattern 150 in positioning the optical head.

A method for generating a tracking servo pattern on optical tape media,as described herein may be performed using an adapted optical tapeprocessing apparatus herein described.

Referring to FIG. 2, optical media base film 210 may be prepared for usethrough a base film oven-extruder & stretcher 220 to deliver opticalmedia base film 210 in a predetermined thickness and tensile strength.The optical media base film 210 may be then processed through a die 230consisting of a plurality of fine feature and pitch openings 250 thatcontact a side of the base film 210. Die 230 constructs alternating highand low grooves 240 that may be narrow in width and run alongsubstantially the full length and across substantially the full width ofbase film 210.

Additionally die 230 can move from side to side, substantiallyperpendicular to the axis of motion of base film 210, as well as up anddown, substantially perpendicular to the plane of base film 210. Themotion of base film 210 through die 230 results in a pattern of finegrooves 240 in base film 210. One possible use of grooves 240 may be forservo tracking.

The up and down motion of die 230 allows precise groove depth control.Carefully controlling the side to side motion of die 230 will generategroves of a predetermined pattern. One such possible pattern may be asinusoidal pattern which may be known to be beneficial for proper servotracking. Die 230 can generate a predetermined groove pitch 260 and apredetermined groove depth 270. While die 230 can be constructed forgenerating a plurality of groove to groove spacing and groove widths,one possible groove to groove spacing may be approximately 0.74 um.

Optical tape media, as herein described may be constructed to supportwrite-once read many operation, or re-writable operation. The operationsupported may be partially determined by the type of layer material andthe order of layers in the optical tape media.

Referring to FIG. 3, an embodiment of a first surface incident(air-incident) WORM optical tape media includes a topcoat 302, anovercoat 304, a phase change layer 308, a reflective layer 310, anembossed layer 312, a basefilm or substrate 314, and a backcoat 318.

Topcoat 302, an organic, scratch-resistant film applied by a sputterprocess, provides a protective layer for the other layers of the media.Topcoat 302 may include anti-reflective properties (e.g. low index ofrefraction) to prevent unwanted reflections of laser light 320 fromlayers within the media.

In the possible embodiment of FIG. 3, overcoat 304 may be an opticallytransparent, near zero absorption protective layer, made from materialsuch as ZnS (tradename ZS80). Alternatively overcoat 304 may alsocontain SiO2 or other such materials that may protect lower layers fromphysical damage. Overcoat 304 may be applied by a sputter process andmay include anti-reflective material to allow laser light 320 topenetrate through it more efficiently.

In this possible embodiment, the phase change coating 308 may be aphase-change alloy such as Ge—Sb—Te, (germanium-antimony-tellurium),however other phase change materials known as a write-bright phasechange material may be included. Write-bright material changes from anamorphous to a crystalline phase when subjected to sufficient heat fromlaser 320. Once changed, the composition of the material prevents itfrom changing back to the amorphous phase. The resulting crystallinespots, being more reflective than the surrounding amorphous material,creating a high contrast against the surrounding area, may be means forstoring data in the WORM optical tape media. Phase change film 308, inthis possible embodiment, may be created using a sputter process.

Reflective layer 310, made of a metal material such as aluminum, orantimony, reflects light from laser 320 that passes through phase changelayer 308. Reflective layer 310 may be created using an electron-beam,may be thermally evaporated, may be sputtered, may be ion beamdeposited, or a like process. Reflective layer 310 further attenuateslight from above, and it also reflects light from below, thusattenuating and blocking any light from above and below from passingthrough and mixing with laser light 320, which may introduce noise inthe nominal reflected laser light 320. Reflective layer 310 may also aidin the crystallization of phase change 308, creating a suitable thermalprofile by facilitating nucleation.

Embossed layer 312, contains the physical land and groove structuresused for servo tracking. Embossed layer 312 may be formed from a monomerfluid by a drum embossing and UV curing apparatus where it may beembossed with the land and groove structures and cured at the same time.While curing, it coverts from a liquid monomer to a solid polymer andmay be permanently attached to substrate 314.

Below embossed layer 312 may be substrate or basefilm 314 which providesmechanical support. Basefilm 314 may be created from a high-performancethermoplastic polyester film such as polyethylene naphthalate (PEN),polyethylene terephthalate (PET), or similar material having appropriatemechanical, thermal, and hydroscopic properties for a data storageproduct.

A backcoat 318 may be deposited on a back side of basefilm 314. Backcoat318 may be a partially conductive layer to minimize the buildup ofstatic charge, and has a textured surface acting as a conduit to releaseentrapped air generated during tape subsystem operation. In addition,backcoat 318 optical properties absorb and scatter incident laser light320 that penetrates reflective layer 310. Backcoat 318 may be one of amaterial selected from a set including carbon black film created byslurry-coating, aluminum sputtered layer, and nickel chromium sputteredlayer.

In an embodiment, the possible embodiment of FIG. 3 may be used formulti-wavelength readback to the optical head.

Referring to FIG. 4, an embodiment of a first surface incident(air-incident) rewritable optical tape media may be shown. In theembodiment of FIG. 4, a dielectric material 402 may be inserted betweenphase change layer 308 and reflective layer 310. Dielectric layer 402restricts heat in phase change layer 308 to a small volume in order tofacilitate a write and erase process. Dielectric layer 402 may consistof ZnS, SiO2, or like material and may be created by a sputter process.The thickness may need to be such that it may be optically transparent.

In the media of possible embodiment of FIG. 4, phase change layer 308may be composed of a crystalline material that allows the use awrite-dark technique. The write-dark technique uses a high intensitylaser to convert areas of the crystalline material into non-reflectiveareas resulting in a written data mark, and uses a medium intensitylaser to erase the data mark by returning it to its crystalline state.

Referring to FIG. 5, an embodiment of a second surface incident(basefilm-incident) media, an alternate ordering of the layers of FIG. 3may be shown. In this embodiment laser light 320 may travel throughtopcoat 302, basefilm 314, embossed layer 312, and overcoat 304, bereflected by phase change layer 308, and travel back to the optical headdetector. The order of the layers in this media may be topcoat 302,substrate or basefilm 314, embossed layer 312, overcoat 304, phasechange layer 308, reflective layer 310, and backcoat 318.

The embodiment of FIG. 5 provides the advantage of keeping anycontaminants on topcoat 302 out of the focal plane of laser 320.Additionally, basefilm 314 may be an optically transparent,low-birefringence material in order to prevent distortion of laser 320as it travels through the basefilm 314. A suitable material for basefilm314 may be polycarbonate, Spaltan PET, or the like.

Referring to FIG. 6, an embodiment of a second surface incident(basefilm-incident) rewritable media may be shown. This embodimentincludes dielectric layer 602 between phase change layer 308 andreflective layer 310. Dielectric layer 602 restricts heat in phasechange layer 308 to a small volume in order to facilitate a write anderase process. Dielectric layer 602 may consist of ZnS, SiO2, or likematerial and may be created by a sputter process. The thickness may needto be such that it may be optically transparent.

Optical tape media may be adapted as herein described to allow highoptical contrast as a result of the media transitioning betweennon-crystalline and crystalline phases.

Referring to FIG. 7A, a possible embodiment of the invention includesphase change media stack 710 having a conventional geometry whichincludes first a thin metal layer 720 on a plastic or glass substrate730, then a phase change layer 740, and then a dielectric layer 750.Phase change media stack 710 may be good for configurations that use anair-incident laser beam 760. Referring to FIG. 7B, an alternate possibleembodiment including an alternate stacking of the layers of FIG. 7A maybe suited for substrate-incidence laser 770 configurations.

In the possible embodiment of FIGS. 7A and 7B, when metallic layer 720may be antimony (Sb), phase change layer 740 may be Te—Ge—Sb (telluriumgermanium-antimony) ternary alloy, and dielectric layer 750 may beZnS/SiO2, media stack 710 exhibits unique write characteristics.

Referring to FIG. 8A, a relatively long write-pulse (approximately 50 nsor longer) at relatively low laser write powers, applied to media stack10-110 results in a written spot 810 that has higher reflectivity thanthe unwritten surroundings 820. In particular, with a relatively longwrite-pulse at relatively low laser write powers the material reachescrystallization temperature, which may be lower than the meltingtemperature and crystallization will take place resulting in a writebright spot 810.

Referring to FIG. 8B, a relatively short write pulse (approximately 20ns or less), and relatively high laser write power, cause both writebright and write dark, which includes written spot 830 consisting of adark center surrounded by a bright ring. The bright ring may be causedby partial crystallization of the phase change material.

Referring to FIG. 9, at the relatively high laser write power, phasechange layer 740 reaches its melting point near the write pulse peak,and surface tension of the molten material draws the material away fromthe laser pulse into a crystallized bright ring 910 and forms a crater920. The crater may be permanent as the material cools off quickly withthe removal of the laser pulse. The contrast of crater 920 to brightring 910 may be far superior to the traditional bright spot 810 in FIG.8A and its unwritten surroundings.

Referring to FIG. 10, a comparison of signal measurements generated bywrite bright 1010 and write dark 1020 shows the superior contrast ofwrite dark 1020 represented by the larger amplitude waveform.

An optical tape system may include a servo tracking system as hereindescribed for use with optical tape media employing a preformatted tracklayout.

Referring to FIG. 11, the formatted optical media 1110 may have asegmented track layout. A tape transport subsystem 1130 moves media 1110at a substantially constant speed relative to a data/servo opticalsensing element 1120. Servo system sequencer 1140 receives a signal fromsensing element 1120 which represents information detected from opticalmedia 1110. Using the information detected, sequencer 1140 selects anoperating mode for servo system 1150 from a set includingInitialization, Calibration, Tracking, Jump-gap, and Jump-track.

In Initialization mode, servo system 1150 performs initialization steps.In Calibration mode, servo system 1150 may determine optimum settingsfor Jump-gap, Jump-track, and Tracking mode. Initialization andCalibration modes may take place during servo system 1150 power-up.

Referring to FIG. 12, a segment 1210 on media 1110 includes tracks 1220with length 1230. Segments 1210 may be separated by gaps (defects) oflength 1240. Within segment 1210, tracks 1220 each exhibit fields ofmodulated wobble indicative of, for example, a Pre-amble 1212, Data1214, or Post-amble 1216, with Pre-amble 1212, in one embodiment,including a plurality of Synchronization 1250 and Address 1260subfields. Post-amble 1216 field may provide a padding area after theend of Data 1214 and may include the same types of information asPre-amble 1212. These fields appear sequentially to servo system 1150 asmedia 1110 moves across optical sensing element 1120, which isconfigured to read the fields of modulated wobble. Because Pre-amble1212 and Post-amble 1216 straddle the gap, the detection of either byoptical sensing element 1120 may signal servo system 1150 that opticalsensing element 1120 is approaching (in the case of Post-amble 1216) ortraveling away from (in the case of Pre-amble 1212) the gap. Pre-amble1212 and Post-amble 1216 thus convey gap location information.

During Initialization and/or Calibration modes, servo system 1150 mayperform the following steps to learn where to position optical sensingelement 1120 in the direction of travel along media 1110 after aJump-gap is performed. Assuming that in this example Data 1214 isinitially positioned adjacent to optical sensing element 1120, servosystem 1150 may command movement of media 1110 (from right to left)until optical sensing element 1120 detects Post-amble 1216. Upondetecting Post-amble 1216, servo system 1150 may further command, for apredetermined period of time (during which sensing element 1120 is notattempting to focus on media 1110), movement of media 1110 (from rightto left) such that the approaching gap and Pre-amble 1212 eventuallypass optical sensing element 1120, and Data 1214 on the other side ofthe gap is positioned adjacent to optical sensing element 1120. Thepredefined time (“first time”) for this commanded movement may bepre-loaded into servo system 1150 based on specifications associatedwith media 1110. Other techniques such as testing, etc. may also be usedto learn the time needed to accomplish such positioning. Servo system1150 may then command optical sensing element 1120 to refocus. Onceoptical sensing element 1120 is refocused on Data 1214, servo system1150 may command movement of media 1110 in the opposite direction (fromleft to right) such that the gap passed earlier begins to approachoptical sensing element 1120. Servo system 1150 may continue commandingthis movement of media 1110 and may track the time (“second time”)associated with this movement until optical sensing element 1120 detectsPre-amble 1212 or losses focus. Upon detecting Pre-amble 1212, servosystem 1150 may record a linear position of media 1110 relative tooptical sensing element 1120 and/or record the “second time.” If,instead, optical sensing element 1120 loses focus and cannot refocus,servo system 1150 may identify media 1110 as defective.

Because the gaps of media 1110 repeat periodically (as discussed herein,media 1110 is embossed by an embossing drum having gaps—thus, forexample, ten rotations of the drum will produce ten sets of repeatinggaps on media 1110), the above steps may be performed for each of thegaps of the periodic set. Servo system 1110 may determine which gap ofthe set it is encountering based on information in Pre-amble 1212 and/orPost-amble 1216 assuming that each gap of the periodic set is associatedwith a unique Pre-amble 1212 and/or Post-amble 1216.

Servo system 1150 now has information to determine where to positionoptical sensing element 1120 at the completion of a Jump-gap operation.For example, assuming servo system 1150 commands movement of media 1110(in either direction) at a generally constant rate, the differencebetween the “first time” and “second time” may be taken to determine aduration of time for moving media 1110 during a Jump-gap operation(during which optical sensing element 1120 is not attempting to focus onmedia 1110). The linear distance to be traveled by media 1110 during aJump-gap operation may instead/also be determined by taking thedifference between (I) the product of the “first time” and the rate ofmovement of media 1110 during the “first time” and (ii) the product ofthe “second time” and the rate of movement of media 1110 during the“second time.” Other scenarios are also possible.

Referring to FIGS. 11 and 13, sequencer 1140 changes selection fromTracking mode to Jump-gap mode when Post-amble 1216 is detected bysensing element 1120. When in Jump-gap mode, a Jump-gap motion over Gap1310 using the settings determined while in Calibration mode discussedabove may be performed. The Jump-gap motion positions sensing element1120 over an estimated track location and Tracking mode may beinitiated.

Since tracks 1220 may not line up across gap 1310, during Initializationand/or Calibration modes servo system 1150 may perform the followingsteps to learn which post-gap track is most closely aligned with a givenpre-gap track. While focused on a particular track (which may be next toan edge of media 1110) having a specified physical address and prior toencountering the first gap of the repeating set of gaps, servo system1150 may command movement of media 1110 in a first direction (from rightto left) and record the specified physical address of the particulartrack. Upon detecting Pre-amble 1214, servo system 1150 may commandoptical sensing element 1120 to generally maintain its position as media1110 (and thus gap 1310) moves past sensing element 1120 (during whichtime, of course, sensing element 1120 is not attempting to focus onmedia 1110). Once gap 1310 has passed by optical sensing element 1120,servo system 1150 may command sensing element 1120 to refocus anddetermine/record the physical track address of the post-gap track it isfocused on. Servo system 1150 may determine the duration during whichoptical sensing element 1120 is not to focus on media 1110 while gap1310 passes by the sensing element 1120 using the techniques describedabove or any other suitable technique. Because tracks 1220 may not lineup across gap 1310, the recorded pre-gap and post-gap track addressesmay not be the same. Servo system 1150 may then assign a single logicaladdress to the recorded physical addresses.

Servo system 1150 may continue the above process for each unique gap ofthe repeating set of gaps. That is, if there are four unique gaps in therepeating set, servo system 1150 may perform the above process fourtimes such that a set of four segmented tracks found to be most closelyaligned and having physical track addresses of n, n+1, n−2 and n+3respectively, for example, will be assigned a single logical address,n*, for example (where n and n* have integer values). This informationmay be stored to the media 1110 via the optical sensing element 1120 (orstored elsewhere) and/or held in a memory associated with servo system1150.

To determine a mapping of physical track addresses to logical trackaddresses for the rest of the tracks of media 1110, servo system 1150may increment and/or decrement the physical track addresses of the foursegmented tracks found to be most closely aligned (using the exampleabove) as well as the corresponding assigned logical address.Specifically (again using the example above), servo system 1150 mayrespectively increment physical track addresses n, n+1, n−2 and n+3 ton+1, n+2, n−1 and n+4, and increment corresponding logical address n* ton*+1, etc. Table 1 shows an example of such incrementing and/ordecrementing to complete the physical to logical address mapping:

TABLE 1 Mapping of physical addresses to logical address Physical TrackAddresses Logical Track Address n − 1, n, n − 3, n + 2 n* − 1 n, n + 1,n − 2, n + 3 n* n + 1, n + 2, n − 1, n + 4 n* + 1 n + 2, n + 3, n, n + 5n* + 2During normal Tracking mode and if, for example, optical sensing element1120 is focused on logical track address n*, servo system 1150 shouldexpect to encounter physical track addresses n, n+1, n−2 and n+3, inthat relative order, as media 1110 (and thus gaps) pass by the sensingelement 1120. Continuing with the above example, if sensing element 1120senses a pre-gap physical track address of n and then a post-gapphysical track address of n+1 after a Jump-gap operation, servo systemneed not perform a Jump-track operation. If however, sensing element1120 senses a pre-gap physical track address of n and a post-gapphysical track address of n−3 after a Jump-gap operation, servo systemmay need to perform a Jump-track operation to find physical track n+1.For example, demodulator/decoder within servo system 1150 may processessynchronization 1250 and address 1260 information to synchronize anddecode the address of the track over which sensing element 1120 may bepositioned. Based on the decoded address, servo system 1150 determines anumber of tracks to Jump in order to move to a desired track, and mayinitiate a Jump-track operation.

Using the settings determined in Calibration and/or Initialization mode,sensing element 1120 moves to the desired track location and initiatesTracking mode. Tracking mode once again decodes the track address and,based on this information, either initiates another Jump-track, orcontinues in Tracking mode. Once the desired track may be verified,Tracking mode may simply utilize a feedback system to follow a trackingsignal (not shown) embedded in the media.

An optical tape media, coded with predetermined patterns, as hereindescribed may be useful to an optical tape system adapted to interpretthe coded patterns.

Referring to FIG. 14, an embodiment of sinusoidal servo signal 1402 anddiscriminator filter output signal 1404 are shown. The frequency ofsinusoid servo signal 1402 may determine the carrier frequency ofmodulation and timing for servo demodulator 1502. In sinusoidal servosignal 1402 each two cycles may represent a cell 1418. Each of cells1418 may carry information on indexing and address bits. A one cyclesinusoidal phase reversal within cell 1418 may indicate an index bit1410; index bit 1410 may signal the beginning of address field 1412 orphase lock loop (PLL) subfields 1414. A plurality of address subfields1418 may make up the full address of servo signal 1402. In any cell 1418of sinusoidal servo signal 1402, the absence of two sinusoidal cyclesmay indicate a zero bit and the presence of two sinusoidal cycles mayindicate a one bit of the address, therefore address field 1412 may berepresented by sinusoidal servo signals 1402.

Discriminator filter output signal 1404 may be a representation of indexbit 1410 of sinusoidal servo signal 1402. In an embodiment, index bit1410 signal amplitude may be greater than a predetermined indexthreshold to indicate index bit 1410; index bit 1410 may signal thebeginning of address field 1412.

Address field 1412 of a track may be repeated many times in the toprovide data signal robustness and improved signal to noise; addressfield 1412 may have M cells for the 2̂m tracks of an optical tape. Theaddress field 1412 may be interleaved by PLL field 1414 of the samelength and may insure the proper operation of PLL field 1414 and asequencer.

Referring to FIG. 15, a block diagram embodiment of a servo demodulatorand decoder 1502 may be shown. Servo demodulator and decoder 1502 mayinclude a discriminator filter 1504, a threshold detector 1508, a PLL1510, a synchronizer 1512, a synchronized rectifier 1514, a synchronizedresettable integrator 1518, and a second threshold detector 1520.

Discriminator filter 1504 may detect an index pulse from a patternsignal detected from the media. Index pulse (IdxPls) signal 1604 may beused for Phase Lock Loop (PLL) 1510. A VCO signal from PLL 1510 may besynchronized by synchronizer 1512 and used for synchronizedrectification 1514 and resettable integration 1518 of SigIn 1522.Threshold detector 1520, receiving out of synchronized resettableintegrator 1518 may enable the detection address 1412.

Referring to FIG. 16, an embodiment of signals generated by servodemodulator and decoder 1502 may be shown. SigIn 1602 representssinusoidal servo signal 1402 and may include index bit 1410, addressfield 1412, and PLL field 1414. IdxPlx signal 1604 may indicate indexbit 1410 at the beginning of address field 1412. SigRec 1608 may be therectified signal of SigIn 1602 signal that may contain the rectifiedsignals for index bit 1410, address field 1412, and PLL field 1414.IntOut 1610 and AddPls 1612 signals may represent address field 1412output from servo demodulator and decoder 1502.

Writing permanent and distinguishable servo marks on optical tape phasechange media, as herein described, may be useful to an optical tapesystem adapted to interpret the coded patterns.

Methods and systems disclosed herein may include a unique method ofwriting servo marks on optical media that may be permanent in nature andeasily distinguishable from the data.

Referring to FIG. 17, an embodiment of the different phase changeoptical tape media marks 1710 are shown in addition to a read backsignal 1712 received by the optical head. The different media marks 1710may include no marking 1702, a white marking 1704, and a dark marking1708. In an embodiment, the read back signal 1712 polarity may beneutral for no mark, a positive for a white mark 1704, and a negativefor a dark mark 1708. In “write bright” phase change media, the datamarks may be written by applying a specific amount of power to the laserdiode to change the state of the optical media from amorphous(low-reflectivity) to crystalline (high-reflectivity). If the powerapplied to the laser diode exceeds this specific band, the permanentdark mark 1708 (no-reflectivity) may be created on the media which maybe distinguishable from the data write marks 1704 made by the devicesread-write channel, because of its polarity and also its size. The darkmarks 1708 may not be overwritten and may therefore ideal for servopattern formation on the media.

Referring to FIG. 18, an embodiment of embedding servo marks 1812 withdata fields 1810 may be shown. In a sampled servo methodology, the trackaddress and servo positioning information may be embedded in the phasechange media 1802 using the dark marks 1708 during the preformattingmedia process. In an embodiment, formation of the servo marks 1812(servo fields) on an optical phase change tape media 1802 using darkmarks 1708 may be distinguishable from the white marks 1704 data fields1810. The dark mark 1708 servo field 1812 may be embedded into the whitemark 1704 data fields 1810 to provide synchronization and addressinformation for the data fields 1810.

Referring to FIG. 19, an embodiment of the received read back signals1908 for the dark marks 1804 and the white marks 1808 on the opticaltape media 1802 may be shown. As discussed in FIG. 18, the dark marks1802 of the servo field 1812 may be embedded into the data fields 1810of the white marks 1808 on the optical tape media 1802. As shown in FIG.171, the dark marks 1804 may provide a negative read back signal 1902 tothe optical head. The white marks 1808 may provide a positive read backsignal 1904 to the optical head. In an embodiment, the result may be theread back signal 1908 that may provide for a distinguishable polaritysignal for both the dark mark 1804 servo field 1812 and the white mark1808 data fields 1810. The distinguishable polarity of the read backsignal 1908 may allow for reading both the servo field 1812 and datafields 1810 that may be written on the same optical tape 1802 track.

Referring to FIG. 20, an embodiment of a first surface incident(air-incident) WORM optical tape media includes a topcoat 2002, anovercoat 2004, a phase change layer 2008, a metallic layer 2030, areflective layer 2010, an embossed layer 2012, a basefilm or substrate2014, and a backcoat 2018.

Topcoat 2002 maybe an organic, scratch-resistant film applied by asputter process, provides a protective layer for the other layers of themedia. Topcoat 2002 may include anti-reflective properties (e.g. lowindex of refraction) to prevent unwanted reflections of laser light 2020from layers within the media.

In the possible embodiment of FIG. 20, overcoat 2004 may be an opticallytransparent, near zero absorption protective layer, made from materialsuch as ZnS (tradename ZS80). Alternatively overcoat 2004 may alsocontain SiO2 or other such materials that may protect lower layers fromphysical damage. Overcoat 2004 may be applied by a sputter process andmay include anti-reflective material to allow laser light 2020 topenetrate through it more efficiently.

In this possible embodiment, the phase change coating 2008 may be aphase-change alloy such as Te—Ge—Sb, (tellurium-germanium-antimony),however other phase change materials known as a write-bright phasechange material may be included. When composed of Te—Ge—Sb, phase changecoating 2008 may be approximately nineteen nano-meters thick.Write-bright material changes from an amorphous to a crystalline phasewhen subjected to sufficient heat from laser 2020. Once changed, thecomposition of the material prevents it from changing back to theamorphous phase. The resulting crystalline spots, being more reflectivethan the surrounding amorphous material, creating a high contrastagainst the surrounding area, may be means for storing data in the WORMoptical tape media. Phase change film 2008, in this possible embodiment,may be created using a sputter process.

Metal layer 2030 may be a very thin aluminum layer. In this embodiment,metal layer 2030 may be approximately composed of aluminum approximatelyone to two nano-meters thick.

The energy of a laser impacting a phase change material transfers itsenergy to the material with a three dimensional Gaussian profile. Thecenter of the laser impact area will quickly rise in temperature to thephase change material melting point while the wing area will rise onlyto the crystallization temperature, which may be lower than the meltingtemperature. This energy transfer process produces a “donut” like markwith a hole in the middle surrounded by a bright ring. Such marksproduce the advantages of high contrast and high signal to noise ratio.In addition, the process may be very fast, rendering it possible to usesuch media for recording at very fast data rates. However, without metallater 2030 a laser with read power greater than approximately 0.3 mW maycause read etching, which may be unintended bright tracks in the phasechange layer of the media.

Metal layer 2030 enhances the media such that it not only provides allthe desirable characteristics of a high contrast and fast WORM media,but also may be very resistant to read etching. A laser with read poweras high as at least 0.8 up to as much as 1 mW will not cause a readetching problem with this embodiment. In this embodiment, not only maybe the sensitivity to read etching reduced, but also the carrier tonoise ratio of write marks may be improved by about 5 to 10 dB overoptical media without metal layer 2030.

Metal layer 2030 may contribute these advantages by acting as a barrierto prevent migration of metal in reflective layer 2010 into phase changelayer 2008 during laser writing. Alternatively it may be possible thatsome atomic aluminum in metal layer 2030 may migrate into phase changelayer 2008 during deposition. Such migration may retard the phase changelayer 2008 crystallization process while not materially altering themelting temperature.

Reflective layer 2010, made of a metal material such as aluminum, orantimony, reflects light from laser 2020 that passes through phasechange layer 2008 and thin metal layer 2030. When composed of antimony,reflective layer 2010 may be approximately twenty to thirty nano-metersthick. Reflective layer 2010 may be created using an electron-beam, maybe thermally evaporated, may be sputtered, may be ion beam deposited, ora like process. Reflective layer 2010 further reflects light from below,attenuating and blocking any light from below from passing through andmixing with laser light 2020, which may introduce noise in reflect laserlight 2020. Reflective layer 2010 may also aid in the crystallization ofphase change 2008, creating a suitable thermal profile by facilitatingnucleation.

Embossed layer 2012, contains the physical land and groove structuresused for servo tracking. Embossed layer 2012 may be formed from amonomer fluid by a drum embossing and UV curing apparatus where it maybe embossed with the land and groove structures and cured at the sametime. While curing, it coverts from a liquid monomer to a solid polymerand may be permanently attached to substrate 2014.

Below embossed layer 2012 may be substrate or basefilm 2014 whichprovides mechanical support. Basefilm 2014 may be created from ahigh-performance thermoplastic polyester film such as polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), or similar materialhaving appropriate mechanical, thermal, and hydroscopic properties for adata storage product.

A backcoat 2018 may be deposited on a back side of basefilm 2014.Backcoat 2018 may be a partially conductive layer to minimize thebuildup of static charge, and has a textured surface acting as a conduitto release entrapped air generated during tape subsystem operation. Inaddition, backcoat 2018 optical properties absorb and scatter incidentlaser light 2020 that penetrates reflective layer 2010. Backcoat 2018may be one of a material selected from a set including carbon black filmcreated by slurry-coating, aluminum sputtered layer, and nickel chromiumsputtered layer. Backcoat 2018, when made of aluminum, nickel chromium,or other metallic material may also be applied to magnetic tape media toachieve similar static discharge and release of entrapped air.

FIG. 2 may be a representation of waveforms of test signals capturedwhile performing a 3T operation on the media depicted in FIG. 20, withthe media adapted by removing overcoat 104. Because overcoat 2004 may bean optical antireflection interference layer, it does not affect theworking of the remaining layers of media in a significant way during the3T write operation.

Signal 2110 depicts a time domain voltage measurement of a read signalrepresenting the results of reading laser marks on the media. Signal2120 depicts a control signal used to determine when the read signal hasrelevant data. As can be seen in FIG. 21, during the period when signal2120 may be low 225, the read signal has relevant data. Signals 2110 and2120 may be captured and displayed on the oscilloscope using a 5 ms perdivision time scale. Using the capabilities of the oscilloscope, arepresentative portion 2130 of the read signal, may be selected anddisplayed using a 1.46 us per division time scale as signal 2140. To oneskilled in the art, the waveforms of FIG. 21 depict carrier-to-noisecharacteristics of the embodiment of optical media depicted in FIG. 20.

Sensitivity plots may be a derivative tool showing the effect of “micro”changes on a “macro” property. FIGS. 22, 23, 24, and 25 show thereflection sensitivity to changes in the thickness of each layer in athin film stack. In FIGS. 22 and 23 only the last layer may be ofprimary interest; in FIG. 24 the first and third may be of primaryinterest, in FIG. 25 the second and fourth layers may be of primaryinterest.

In both designs shown in FIGS. 22, 23, and 24, note that the amorphousand crystalline curves may be parallel and the amorphous curve may bealways lower than the crystalline one. FIG. 23 may be an extension ofFIG. 22 to show the curves remain parallel even with ten times the layerthickness. An extended curve of FIG. 24 would show the same phenomenaand may be omitted.

FIG. 25 shows an embodiment with amorphous and crystalline curves whichcross. This means one can design a phase change system (e.g. as part ofoptical tape media) to be either high reflectivity in the amorphousstate and low reflectivity in the crystalline state, or highreflectivity in the crystalline state and low reflectivity in theamorphous state. This may be either a write bright or a write darksystem.

For example, a conventional DVD disk would not work properly in a WORMdisk player because the WORM disk player would be looking for anincrease in reflectivity when the disk may be exposed the WORM laserbeam while the DVD disk would decrease in reflectivity when exposed tothe laser beam.

However a LOTS drive may be a WORM drive and the only way erasable tapecould be used in a LOTS drive may be if erasable tape could be made suchthat its reflectivity increases when exposed to a laser beam. The designdepicted in FIG. 26 shows reflectivity increases when exposed to a laserbeam at a wavelength of 532 nm, corresponding to a LOTS wavelength.

In embodiments, a four layer optical tape, composed of phase changelayers, amorphous to crystalline reflectivity change may change frompositive to negative as the thickness of the layers changes.

A media (e.g. optical tape media) with amorphous and crystallinereflectivity curves which cross can be either high reflectivity in theamorphous state and low reflectivity in the crystalline state, or highreflectivity in the crystalline state and low reflectivity in theamorphous state. This may be either a write bright or a write darksystem.

In embodiments, a four layer optical tape, composed of phase changelayers, amorphous to crystalline reflectivity change may change frompositive to negative as the thickness of the layers changes.

An initializer for optical media may comprise a high power laserdelivering energy to an optical media sufficient to initialize a phasechange media to a crystalline state. The high power laser may beautomatically focused onto the phase change layer of the media by alower power laser. However a lower power laser may be saturated when amedia with parallel reflectivity curves (e.g. as shown in FIG. 27) maybe initialized.

In embodiments a four layer optical tape, whose phase changereflectivity curves may be not parallel, may be initialized with a highpower laser automatically focused by a lower power laser wherein thelasers' wavelength may be approximately at that which the reflectivitycurves intersect (e.g. as shown in FIG. 28). Therefore, an initializerapparatus whose focusing wavelength may be approximately equal to themedia reflectivity cross over wavelength may not be saturated. Such anapparatus may be advantageous with phase change materials with shorterwavelengths.

A novel formulation (REWORM) would include depositing in a highreflectivity amorphous state, initialization to a low reflectivitycrystalline state, and writing to a high reflectivity amorphous state.

An advantage of this formulation may include faster erase times becausewriting to the amorphous state from the crystalline state does notdepend on the phase change media's intrinsic crystal growth mechanismwhich includes a constraint of minimum time to change from amorphous tocrystalline states.

An apparatus may be disclosed herein which can erase a tape by returningthe phase change media to a low reflectivity state. Such an apparatuswould erase any information written on a tape in a high reflectivitystate by changing the high reflectivity information to a lowreflectivity state.

Such an apparatus may be useful as a stand alone device, separate fromanother device used to write and read information on the tape.

In particular, such an apparatus may be useful in applications usingwrite bright tape.

An apparatus may be herein disclosed which, when used with optical tapemedia, writes information to the tape, masking any previously writteninformation on the tape, rendering the previously written informationunreadable by an optical tape reading apparatus.

This may have the advantage of preventing sensitive information on atape to be masked such that the sensitive information previously writtento the tape would not be readable. This advantage would benefit a firstuser with sensitive information on optical tapes that must be erased byan optical tape system because it prevents a second user of the opticaltape system from reading the sensitive information before performing theerasing.

Erasable phase change tape media may be manufactured on a continuoussputter coating machine in which all the layers may be simultaneouslydeposited to the media. This may be accomplished by depositing a secondlayer on top of a first deposited layer shortly after the first layermay be deposited, and simultaneously depositing the first layer onfurther portions of the media. In an embodiment, this may achieved bypositioning sputter (layer depositing) sources around a rotating heatextracting drum (chill drum) and moving the media past each sputtersource sequentially. Thin films may be deposited as described above withthe first layer being deposited on a web of polymer type material whichmay be in contact with the chill drum as the media moves past eachsputter source.

Applying this technique to Tellurium-based erasable phase changeformulations of one or more of the deposited layers, may enableproducing graded material interfaces between layers.

Advantages of this media with graded material interfaces between layersmay include strain relief or thermal conductivity transition, which mayresult in improved performance to the resultant phase change structure.Such improved performance may be exhibited as reduced signal jitter orincreased erase cycleability.

In embodiments, different gradations for each interface throughout themultilayer media may be desirable.

Aspects herein may relate to improved optical pick up head systemsadapted for reading and/or writing data from/to optical tape. Theoptical head may be capable of reading and/or writing data on an opticaltape. The optical tape may include formatted digital data in a phasechange layer and it may be adapted to be written upon, re-written upon,erased and/or read from. The optical head may include a transportfacility for the optical head, a read head, a write head, a read/writehead, a direct read after write head, an articulation unit for opticalhead positioning, demodulation facility for decoding the data on theoptical tape, and the like. The optical head may include a light source,a lens, an actuator, a beam splitter, a beam polarizer, an electro-opticintegrated circuit, and/or other systems.

It should be understood that the optical head may be capable of reading,writing, reading and writing, directly reading after writing, or it maybe otherwise configured to meet the needs of the particular application.Several different aspects of the optical head and related facilities aredescribed herein; the different aspects may be combined into an opticalhead or may be used individually.

In an embodiment, an optical pickup head (OPH) as described herein maybe used in a direct read after write (DRAW) mode with optical tapemedia.

In an embodiment, a low power direct read after write (DRAW) laser diodemay be used in conjunction with a higher power laser diode in a pick uphead (PUH). The two laser diodes may have essentially the samewavelength. In an embodiment, a Holographic Optical Element (HOE) may beinserted in the DRAW laser beam path, and the +1 (first order) and −1beams may be used for the DRAW function. The +1 first order beam may beused in a first of media motion while the −1 first order beam may beused in a second direction.

There may be two methods of realizing the DRAW function in the PUH. Anembodiment of the first method may be having a higher power laser diodeLD1 2902 for writing only and a lower power second laser LD2 2914 thatmay have essentially the same wavelength for read, servo read, and DRAW.The beams from the two lasers may be combined to produce all therequired functions in the PUH in addition to DRAW. An embodiment of thesecond method may be having LD1 2902 be used for the write, read, andservo functions, while the lower power LD2 2914 may be for the DRAW.

Referring to FIG. 29, an embodiment of the DRAW based method one havinga higher power laser diode LD1 2902 for writing only and a lower powersecond laser LD2 2914 that may have essentially the same wavelength forread, servo loop, and DRAW may be shown. There may be two optical paths,one for the high power laser diode LD1 2902, and the other for the lowpower laser diode LD2 2914. The path associated with LD1 2902 may be todeliver write energy to the media. The collimator denoted as COL1 2904may be an astigmatic lens providing a collimated and astigmatism freebeam that may be focused by the objective onto the optical tape media.

The path associated with LD2 2914 may be more complex to provide theread, servo loop, and DRAW functions. The holographic optical element(HOE2) 2920 associated with this path may contain a grating and ahologram as shown in FIG. 31. The grating 202 may split the outgoingcollimated beam into 3 beams, namely, the 0th order and the +1st orderand the −1st order beams. The 0th order beam may be used to provide boththe servo functions of focusing and tracking and may provide a nominalreading function. The + and −1st order beams may be used for the DRAW.HOE2 2920 may contain a phase hologram 204, that may diffract thereturned +/−1^(st) order beams in the orthogonal direction to create 6spots on a segmented detector. The signals from the segmented detectorarray may be utilized to generate focus and tracking signals, as well asthe DRAW signals simultaneously. The segmented detector array and thesignal amplifiers may be integrated onto one electro-optic integratedcircuit EOIC2. Since LD2 2914 may be a lower power laser diode, it maybe integrated with the EOIC.

The two collimated beams from LD1 2902 and LD2 2914 may be combined atthe objective lens to maintain the focus of LD1 2902 and LD2 2914.

The distance between the focus point of the 0^(th) order beam and the+,−1^(st) order beams may be controlled by the focal length of theobjective lens, f_(obj), and the grating 202 pitch, A, of HOE2 2920through the formula:

$d = {{f_{obj} \cdot \alpha_{\pm 1}} = {\frac{\lambda}{\Lambda}f_{obj}}}$

where λ may be the LD wavelength.

For example, if a Λ of 0.1 mm, LD wavelength of 650 nm, and f_(obj) of2.5 mm may be used, then α₊₁ equals 37 degrees and d equals 13 microns.

Referring to FIG. 30, an embodiment of a DRAW optical pickup based onmethod two for optical media (e.g. optical tape) may be shown. There maybe two optical paths through the optical pickup, one for the main orprimary beam, and another for the second beam used for the DRAW. Theprimary beam may be used mainly for writing, focus, tracking, andnominal reading.

The light source LD1 2902 may be collimated by lens COL1 2904 and thenthrough holographic optical element (HOE1) 3008. The HOE1 structure maybe the same as described in FIG. 31. The grating in this case may beneeded only to utilize a three-beam tracking scheme. If a singlereturned beam to generate focus and track signals may be used, thegrating may not be needed. A hologram may be used to diffract thereturned beam to the sides of the LD1 2902 source.

The laser source LD2 2914 may be collimated by lens COL2 2918 and thenby HOE2 2920. Since the purpose of the second beam may be direct readafter write, HOE2 2920 may be for this purpose. The grating in HOE2 2920may be a 0th (zeroeth) order suppression grating with most of the energydiffracted in the +/−1 orders as shown in FIG. 32. The +1 order may beahead of the focus of the primary beam spot, and the −1 order behind theprimary beam spot, as far as the tracking direction goes. One order maybe used for DRAW when the media may be moving in a first direction andthe other may be used when the media may be moving in a seconddirection.

It may be important to have the right groove depth in holographicelement HOE1 3008 in order to control the 0th order suppression. Forexample, if the holographic element HOE1 3008 may be a glass plate witha refractive index of 1.55, the groove depth may need to be 550 nm whenusing a light source with a wavelength of 655 nm to completely suppressthe 0th order beam. Complete suppression of the 0th order beam may bedesirable but may not be necessary. That is, one may use smaller groovedepths. For example, at a depth of 380 nm, the energy may be evenlydistributed in the three order beams −0, +1, and −1. This may workadequately. More 0th order energy may be undesirable since it couldcause more Relative Intensity Noise (RIN) noise.

As shown in FIG. 32, holographic element HOE2 2920 may also contain aphase hologram. The purpose of the phase hologram may be to diffract thereturned ±1st order beams into the correct location for data detection.

Referring to both FIG. 29 and FIG. 31, the primary and secondary beamsmay be merged together using a polarizing beam splitter, PBS 2910. Withthe polarizing beam splitter PBS 2910, the reflected beams may return totheir own original directions.

Referring to FIG. 33, another feature may be the orientation of the twolaser diodes. The polarization directions of the two beams may beessentially perpendicular to each other. For example, light source LD12902 may be polarized in a direction that may be mainly parallel to thedirection of tape motion and the media plane, and light source LD2 2914may be polarized in a direction that may be perpendicular to tape motionbut may be parallel to the plane of the media. This may make it possibleto combine the two beams at the polarizing beam splitter PBS 2910. Sincethe single spatial mode light coming out of a laser diode may bepolarized mostly parallel to the P-N junction plane 3402, the P-Njunction planes 3402 of light source LD1 2902 and light source LD2 2914may be perpendicular to each other.

Many other versions of optical path arrangements for the two beams maybe possible if the laser diodes are not integrated into theelectro-optic integrated circuit detector array. However, suchconfigurations may be less compact than the integrated LD-EOIC array.Another version of the DRAW pickup head may be shown in FIG. 34, wherethe laser diodes and the two electro-optic integrated circuits may beintegrated onto one silicon chip.

Since mounting two laser diodes on one silicon chip at an angle of 90°to each other, as shown in FIG. 33, may present some manufacturingchallenges, two other versions are shown in FIG. 35 and FIG. 36, wherethe two laser diodes have an identical orientation. The embodiment shownin FIG. 35 may provide the same function as the first embodimentdiscussed in FIG. 29. The embodiment shown in FIG. 36 may provide thesame function as the embodiment discussed in the FIG. 30 based methodtwo. However, in these versions, another birefringent plate 3602 may beadded to the second beam to rotate its polarization by 90°.

Since, in embodiments, light source LD 1 2902 may be used for writingwhile light source LD2 2914 may be used for DRAW read, the light sourceLD2 2914 power requirements may be much less demanding, and less costly,lower power lasers may be used for light source LD2 2914.

In an embodiment, an optical pickup head (OPH) may be adapted to permita large tracking range of optical media (e.g. optical tape) as describedherein.

Referring to FIG. 37, an embodiment of a conventional PUH 3702 (FIG.37A) and an embodiment of the integrated electro-optic assembly 3704(FIG. 37B) are shown. Using the optical actuator 3708 to move just theobjective lens may lead to undesirable beam movement in relation to theremainder of the optic assembly; this may lead to servo tracking errorsas the beam focal point moves away from a proper position range. Usingthe optic assembly 3704 the entire optical lens assembly may be moved bythe actuators 3710 to track the optical tape. This may maintain theproper position of the return beam on the electro-optic integratedcircuit 3712. Thus the tracking range may now be based on the range ofthe actuator rather than by optical vignetting and beam walking problemsdiscussed below.

Referring to FIG. 38, an illustration shows the optical vignettingcaused when only the objective lens may be moved to track the opticaltape tracks. Conventional pick up heads (PUH) may have track rangelimitations due to problems caused by optical vignetting and beamwalking. When the track center may be near the center of the Gaussianbeam profile before emerging from the objective lens, a perfectpush-pull pattern may be obtained on the quad detector.

When the track under consideration moves downward from a first position3804 to a second position 3808 due to media runout, the servo loop maycause the lens to also move downward. The focal point will thus try tofollow the track center; however, this may cause the Gaussian beamprofile impinging on the objective lens to be no longer centered on theaperture. This slight imbalance may cause the push-pull pattern at thedetector 3802 to also be imbalanced, resulting in a small error signal.A finite conjugate objective lens 3810 may be used where the beamimpinging on the objective lens has a divergent wave front. When thelens moves to follow the track runout, the return beam may suffer from abeam walking problem on the detector 3812.

In the conventional PUH embodiment, the imbalanced push-pull pattern andbeam walking at the detector may create less desirable beam position atthe electro-optic integrated circuit EOIC. The less than desirable beamposition may limit the number of tracks that the PUH may be able tocover to tens of tracks.

Referring to FIG. 39, an embodiment of the invention may be shown withthe electro-optic integrated circuit (EOIC) 3902, laser diode (LD) 3904,astigmatic lens 3908, holographic optical element (HOE) 3910, actuator3912, and objective lens 3914 all part of a single assembly 3918. Bymoving the objective lens 3914 with the assembly 3918, the opticalvignetting and the optical shift problems may be eliminated. To positionthe pick-up head (PUH) assembly 3918 accurately requires sufficientservo bandwidth and thus the assembly 3918 may require a low weight. Thelow weight may be provided by an integrated design.

In the integrated design, the laser diode LD 3904 may be mounteddirectly on the electro-optic integrated circuit EOIC 3902. Theelectro-optic integrated circuit EOIC 3902 may include a silicon chipwith a segmented detector, a current amplifier, and a voltage amplifier.A simple grating may be used for the holographic element HOE 3910; theholographic element HOE 3910 may divide the beam into 0th and ±1 orders.The 0th order may have 50% efficiency while the ±1 orders may haveapproximately 25% efficiency each. The 0th order beam may be used forread/write, as well as the focus/track functions. When the 0th orderbeam may be returned to the holographic element HOE 3910, the two firstorder beams may be diffracted to the left and right six-segmentdetectors of the electro-optic integrated circuit EOIC 3902. Each one ofthe diffracted beams may be used for focus/track and read/writefunctions. The signals in the two segments may be equivalent and may besummed to improve the SNR (signal-to-noise ratio) by 3 dB.

In another embodiment, the simple grating may be replaced by an on-axishologram. It may provide both positive and negative lensing effects suchthat, for example, one six-element segment may receive light from beforethe best focus, while the other six-element segment may receive lightfrom after the best focus on the media. This may allow for adifferential spot focusing method to be used. Another significantadvantage of the hologram may be that the two first order beams in theoutgoing beam may be out of focus; this may produce a low amount ofreturn light into the detector. The two first order spots may beunwanted and therefore the low return light may be ignored.

In an embodiment, by moving the entire assembly when tracking theoptical tape media, the optical-electric assembly may maintain abalanced push-pull pattern without beam walking at the detector on theelectro-optic integrated circuit EOIC 3902. The improved focus with aconsistent balanced push-pull pattern of the optical-electric assemblymay provide for a greater number of covered tracks on the optical tape;the integrated optical-electric assembly may be able to cover thousandsof tracks.

Referring to FIG. 40, an embodiment of a Direct Read After Write (DRAW)feature may be shown incorporated into the integrated design assembly3918. The DRAW may be described further in FIG. 29 through 34. The DRAWmay be an additional low power laser diode that may provide a ±1 orderbeam. The ±1 order beam may allow the optical pickup head (PUH) toperform a read immediately after a write to minimize write errors. Theincorporation of the DRAW into the integrated design assembly 3918 mayprovide the same improved tracking to the DRAW as the primary beamreceives from tracking the entire assembly 3918.

In an embodiment, a transport as described herein may be adapted fortransporting multiple optical heads used to interface with optical tapein an optical tape facility.

The tape drive may have a tape guiding system without any discreteguiding mechanism between a removable cartridge reel and a take-up reel.When the removable cartridge may be inserted into the tape drive themedia may be pulled onto the take up reel using a take up leader thatmay attach to the leader material in the media cartridge.

Referring to FIG. 41, an embodiment of a re-orientation of the opticalhead transport facility at the tape position extremes may be shown. Ahead transport facility 4102 may be positioned between the cartridgereel 4104 and the take up reel 4108. The head transport facility 4102may be located on a mechanism that may allow for lateral positioningsuch that the distance from the head transport facility 4102 to themedia may be controlled; the head transport facility 4102 may berequired to be a distance from the media for optimal read/writeoperations. As the media may be moved from the cartridge reel 4104 tothe take up reel 4108 the head transport facility 4102 mechanism mayadjust for the changing distance to the media. The head transportfacility 4102 may also adjust for the changing angle of the media to thehead transport facility 4102 as the media may be transferred between thereels. In an embodiment, as the media moves from the cartridge reel 4104to the take up reel 4108 the angle and distance relative to the headtransport facility 4102 may change based on the amount of media on eachof the reels; the angle and distance may continuously change duringoperation of the tape drive. The exact position of the head transportfacility 4102 may be determined by an algorithm in the compensationsystem of the servo controlled mechanism.

Multiple heads may be used in a single head transport facility toincrease the data transfer rate of an optical drive. Each individualhead may use it's own servo control positioning system for the accuratepositioning of the head, then the head transport facility 4102 may beused to approximately position the array of heads close to the tape.This may greatly minimize the complexity of using many optical heads.

Referring to FIG. 42, the head transport facility 4102 may include aplurality of optical heads 4202, each with its own servo controlledactuator and positioning system. The optical heads 4202 may be arrangedsuch that each optical head 4202 may be responsible for reading andwriting data in a zone 4204 of optical tape. In an embodiment, a zone4204 of the optical tape may be a number of optical tape tracks. Theremay be enough optical heads 4102 in the head transport facility 1102 tocover all of the tape's zones 4204 or tracks. Each optical head 4202 maybe capable of being positioned to any of the recording tracks within theoptical head's 4202 zone 4204 without affecting the other optical heads4202; the range of motion of each optical head 4202 may be entirelywithin the servo controlled actuator range of motion. Additionally, thefocusing control for each optical head 4202 may have enough range ofmotion to permit each optical head 4202 to maintain focus during therotational motion of the tape as it moves from the beginning to the endof the optical tape; the maintaining of focus may be in either directionof optical tape motion.

Referring again to the tape drive of FIG. 41, there may not be guidingmembers 4112 to fix the position of the optical tape, therefore the headtransport facility 4102 may move laterally and rotate to maintain aproper orientation with the optical tape. In an embodiment, the headtransport facility 4102 may have it's own closed loop servo system withinformation originating from the individual optical heads 4202. Anadvantage of this system may be that the head transport facility 4102may use sensor information from the optical heads 4202 there may not bea requirement for extra sensors for the head transport facility 4102.

Systems and methods may also allow for a head transport facility 4102 onboth sides 4110 of the media, at least two head transport facilities4102 4110 may be connected to the same head transport system.

FIG. 42 shows an embodiment of the head transport facility containing anumber of individual heads 4202. In an embodiment, the number ofindividual optical heads 4202 in the head transport facility 4102 may bebased on the size of the head transport facility 4102 and the number oftracks and optical tape width required to be covered. For example, ifthere are one thousand tracks on the optical media and each individualoptical head 4202 may be capable of covering two hundred tracks within azone 4204, there may only be five individual optical heads 4202 in thehead transport facility 4102. In an embodiment, the number of opticalheads 4202 may not be directly related to the number of tracks and thenumber of tracks that each individual optical head 4202 may cover; theremay be a certain number of tracks overlapped between individual opticalheads 4202 and therefore increase the number of optical heads 4202needed for a certain number of tracks. Each optical head 4202 may beindependent in its ability to control both focus and data trackacquisition. Each optical head 4202 may be aligned to any of theplurality of data tracks within a dedicated zone 4204.

In an embodiment, an optical tape drive may be adapted as describedherein for high density storage using optical tape media.

In a typical tape drive there may be rotating rollers that guide themedia from the cartridge reel, past the head transport facility to thetake up reel. One of the purposes of these machined rollers may be toreduce the lateral tape motion created by the cartridge and take upreels; however the rollers themselves may create lateral tape motion athigher frequencies than the reels. In embodiments, servo controlledpositioning systems for the head assemblies may create the ability forsuch a system to compensate for low frequency motion from the reels maybe improved and may be superior to that for the roller higherfrequencies.

Referring to FIG. 43, an embodiment of the re-orientation of the headtransport facility 4102 to the tape extremes 4302 may be shown. Anaspect may have a tape guiding system without any discrete guidingmechanism between the removable cartridge reel 4104 and the take-up reel4108. When a removable cartridge 4104 may be inserted into the tapedrive, the media may be pulled onto the take up reel 4108 using a takeup leader that attaches to the leader material in the media cartridge.

The head transport facility 4102 may be positioned between the cartridgereel 4104 and the take up reel 4108. The head transport facility 4102may be located on a mechanism that allows for lateral positioning suchthat the distance from the head assembly to the media may be accuratelycontrolled. In the case of a no contact recording, the head may berequired to be a certain distance from the media. As the media may bemoved from the cartridge reel 4104 to the take up reel 4108 the angle ofthe tape may be constantly changing as the amount of tape on each reelchanges. As the media may be moved from the cartridge reel 4104 to thetake up reel 4108 the head transport facility 4102 may adjust for thechanging distance to the media. The head transport facility 4102 mayadjust for the changing angle of the media to the head transportassembly 4102. The exact position of the head transport facility 4102may be determined by an algorithm in the compensation system of theservo controlled mechanism.

The lateral tape motion (LTM) in this tape path may originate from thesupply reel 4104 and the take up reel 4108 only. In an embodiment, themanufacturing tolerances for these two components may be controlled toseveral thousandths of an inch larger than the tape width; therefore,the tape may be provided with adequate guidance without the use of guiderollers. The frequency of the LTM may be substantially at the rotationfrequency of the reels; the frequency may be 10 to 400 Hz. Thisfrequency may be significantly less than the frequency the guide rollersmay introduce; guide roller 4112 LTM frequencies may be many hundreds ofhertz. At the lower frequencies, the servo controlled head transportfacility 4102 positioning system may be very efficient using a bandwidthof about 1 kHz. The head transport facility 4102 servo controls may beable to better adjust for the lower frequency LTM created by thereel-to-reel tape motion. The efficient positioning head transportfacility 4102 may have improved tape tracking and therefore may be ableto read and write higher density tape tracks.

While the absence of rotating guiding 4112 members may be relied on, inan embodiment, it may be possible to have one or more fixed non-rotatingguides 4112 for maintaining positional consistency of the media at thehead transport facility 4102.

In an embodiment, this may also allow for using head transportfacilities 4102 4110 on both sides of the media since there may not beextra wear on one side due to guiding rollers 4112. The use of a secondhead transport facility 4110 and recording data on the other side of themedia may also increase the high density recording.

A laser head tracking system may track the position of data on a movingoptical tape media for the purpose of writing data in the correctposition on the media in relation to previously written data on themedia.

Referring to FIG. 44, an embodiment of the invention may be shown. Theremay be a transducer assembly 4402 that may include a laser source 4404,beam splitter 4408, detector 4410, and a movable lens 4412. The moveablelens 4412 may move independent of the rest of the transducer assemble4402 or may be moved with the transducer assembly 4402 as a completeunit. The laser source 4404 may provide light that may be focused on themedia by the movable lens 4412. The light may reflect back through themoveable lens 4412 to the beam splitter 4408 that may direct thereflected light to the detector 4410. The detector 4410 may beassociated with a processor that may be capable of interpreting thelight reflected from the media. The position of information on the mediamay be determined by using the transducer 4402 that may measure theposition of information that may have been previously written to themedia. In an embodiment, there may be a processor that may calculate thenext correct position for information to be written by a writer 4414.The writer 4414 may include a laser source, beam splitter, detector, andmoveable lens. The writer 4414 may have actuators 4424 that may positionthe writer 4414 to a position to write data; the actuator 4424 may movethe moveable lens or may move the entire writer 4414 assembly. Thewriter 4414 may write the new information on the media.

In an embodiment, the writer 4414 may receive positioning informationfrom the transducer 4402 through an error correction feedback facility4418. In an embodiment, the transducer 4402 may read the previouslywritten data 4420 on the media and may feed the positioning informationto the error correction facility 4418; the feed of information may be inreal time. The previously written data 4420 may be received by thetransducer detector 4410; the detector 4410 may feed the previouslywritten data 4420 position to the error correction feedback facility4418. The correction feedback facility 4418 may also receive previouslywritten data 4420 positioning information from the moveable lensactuators. In an embodiment, the error correction feedback facility 4418may contain logic to combine the previously written data 4420positioning information from both the transducer detector 4410 andmoveable lens actuator. In an embodiment, the error correction feedbackfacility 4418 may calculate the next position 4422 to write information;the next position 4422 may be feed to the writer 4414.

In an embodiment, the writer 4414 may receive the positioninginformation from the error correction feedback facility 4418. In anembodiment, the writer 4414 may receive the positioning informationdirectly to the writer actuators 4424. In an embodiment, the writer 4414may receive the positioning information to a processor that maycalculate the next position 4422 for writing data to the media. In anembodiment, the next position 4422 for writing data may be in relationto the previously written data 4420 read by the transducer 4402.

In an embodiment, the next written data 4422 may be a set position fromthe previously written data 4420; the set position may be part of theread/write logic and therefore may not require positioning informationto be written into the written data 4422.

In an embodiment, the next written data 4422 may not be a set positionfrom the previously written data 4420; the data spacing may be writtenas part of the data written to the media.

In an embodiment, the next written data 4422 may be a set position basedon a system variable; the system variable may be based on the requireddata density. In an embodiment, the position information may not bewritten into the written data 4422. In an embodiment, the systemvariable may be stored in the transducer 4402, the writer 4414, theerror correction feedback facility 4418, or the like.

In an embodiment, multi-demodulation of received signals may be includedin an optical tape facility for fast and accurate signal processing.

Modulated signals received by a multi-demodulator may represent aplurality of information such as amplitude, phase, frequency, and thelike. The information may be a transmitted communication signal, atemperature, a position and velocity of an electromechanical devicereceived electronically, or the like.

These modulated signals may also identify different types of productsand their properties such as product type, product serial number,product distinguishing factors, attributes transmittable electronicallyor optically, and the like.

The multi-demodulator may determine the type of the received signal andan instantaneous value based upon the shape and carrier frequency; thisinformation may be provided to a host device. The host device may applya set of rules and decisions for the operation of the device based onthe type and instantaneous value information provided by thedemodulator.

The real time demodulation capability of this system may enable anapplication a fast and accurate signal processing for applications suchas real time data and signal processing in communication systems,electromechanical control systems, and the like.

Referring to FIG. 45, a high level embodiment of the demodulator 4500may be shown. The demodulator 4500 may include a signal modulator inputdevice 4502 to receive and condition the signals and a signaldemodulator device 4504 that may demodulate the combined signal S(t) toindividual outputs. The conditioning of the signals may include signalamplification, signal filtering, analog to digital conversion, or thelike. A modulated signal S(t) may be received by the demodulator 4500and may be a single modulated signal representing one of many types ofmodulated signals with different carrier frequencies as described byEq1. The modulated signal S(t) may be a sum of these modulated signalsas in Eq2.

S(t)={S1(t)*sin(w1*t)} Or {S2(t)*sin(w2*t)} . . . Or{Sk(t)*sin(wk*t)}  (Eq1)

Or

S(t)={S1(t)*sin(w1*t)}+{S2(t)*sin(w2*t)}+ . . . {Sk(t)*sin(wk*t)}  (Eq2)

The demodulator 4500 may be able to determine the presence of theplurality of Sk(t) signals in the received signal S(t) and may also beable to demodulate the instantaneous values of any Sk(t) signalspresented in S(t).

Referring to FIG. 46 a more detailed embodiment of the demodulator maybe shown. In an embodiment, the signal S(t) may first be conditioned bya device input interface (Din) 4502 and then may be processed by a setof complimentary filters in the signal demodulator 104:

[FP1&FQ1], [FP2&FQ2], . . . [FPk&FQk]

The complimentary filters may determine the presence and type of thedifferent signals Sk(t) in the S(t) signal and may report the type ofsignal by a set of output signals.

TYP1, TYP2, . . . TYPk

and their instantaneous (real-time) magnitudes by:

S1(t), S2(t), . . . Sk(T)

The demodulation process may be either analog or digital. The functionof the Din 4502 in the analog design may be to adjust the level andamplitude of input signal S(t) for processing. In the digital design theDin 4502 may be an analog to digital converter (ADC) and the level andamplitude of S(t)n (S(t)n=sampled S(t) at Ts sample rate) may beadjusted later in by a system microprocessor or an application specificintegrated circuit (ASIC). The operation of the complementary filtersmay be:

[FP1&FQ1], [FP2&FQ2], . . . [FPk&FQk]

The received signal S(t) may be described in the set of equations:

P 1 = S(t) * L(t)1 Q 1 = S(t) * M(t)1 P 2 = S(t) * L(t)2Q 2 = S(t) * M(t)2 ⋮ P k = S(t) * L(t)kQ k = S(t) * M(t)k

Where L(t)k may be a rectangular function with the frequency wkassociated with the carrier frequency for signal {Sk(t)*sin(wk*T)}.M(t)k may be a rectangular function with a frequency wk, the frequencymay be 90 degrees out of phase with L(t)k signal.

Further processing may produce:

FP 1 = AVE(P 1) FQ 1 = AVE(Q 1) FP 2 = AVE(P 2)FQ 2 = AVE(Q 2) ⋮ FP k = AVE(P k) FQ k = AVE(Q k)

Where AVE (Pk) and AVE Q(k) may be the running sum averages in real timeof the Pk and Qk signals.

From the Fourier Transformation theorem the following derivations may bemade:

S 1(t) ∝ FP 1 + FQ 1 S 2(t) ∝ FP 2 + FQ 2 ⋮S k(t) ∝ FP k + FQ k

where ∝ indicates the proportionality.

Thus, the amplitude of any signal Sk(t) or its presence or non presencein S(t) may be determined in this method.

In an embodiment, an optical tape facility as described herein may beconfigured for error correction using multi-channel ECC interleaved within-line ECC.

User data may be formatted into logical Kbyte blocks of data. For thelogical Kbyte blocks of data, ECC symbol blocks may be generated tocreate an ECC entity that may include the logical Kbyte blocks of dataand the ECC symbol blocks. This ECC entity may be referred to as the ECCcoding scheme (C+D, D) where C+D may be the total number of blocks thatmake up the ECC entity and D may be the number of ECC blocks that may begenerated. D may also be the number of blocks that may be corrected inthe ECC entity during reading of the tape.

Once data may be formatted into ECC entities, the blocks of data thatmay make up the entity may be encoded with a per channel ECC that maycorrect bytes of error data out of the Kbytes blocks of data. Theformatted data blocks may be interleaved to create an ECC block to berecorded on the tape. The ECC block may be a multiple interleaved blockfrom the channel ECC entity to form a multi-block recorded ECC frame onthe tape.

In an embodiment, during the read process the inline ECC may correct upto 10 bytes of data in error per logical Kbyte blocks of interleaveddata. As data may be read, any blocks that may be in error may becorrected for up to about 10 bytes. If the ECC cannot correct the data,the block in error may be corrected by the cross-channel ECC that mayuse data recorded in other tracks on tape.

In an embodiment, a servo tracking system may be described for multipleoptical heads of a transport facility that may provide a feed forwardtracking signal for the multiple optical heads.

Referring to FIG. 47, a formatted optical tape media 4710 may havemultiple track zones 4702 (N track zones). There may be multiple tracks4704 (K tracks) within each of the multiple track zones 4702.

Each multiple track zone 4702 may have it's own dedicated opticalread/write head 4708. In this manner, data may be written and read fromthe optical media 4710 in a parallel data streaming fashion as theoptical tape moves past the stationary heads 4708.

A track misregistration (TMh) for each multiple track zone 4702 may begoverned by two major components. The track misregistration may be themovement of an individual track in relation to the optical head 4708.Lateral tape motion (LTM) 4712 may be common for all the heads 4708 anda residual motion 4714 (RMh) of each head 4708, which may be specific toeach head. LTM 4712 may be the motion of the optical tape media 4710 inrelation to the head transport facility. Thus:

$\begin{matrix}{{{{TM}\; 1} = {{LTM} + {{RM}\; 1}}}{{{TM}\; 2} = {{LTM} + {{RM}\; 2}}}{{{TM}\; 3} = {{LTM} + {{RM}\; 3}}}\vdots {{{TM}\; N} = {{LTM} + {{RM}\; N}}}} & {{EQU}\mspace{14mu} 1}\end{matrix}$

The servo sensing head for each multiple track zone 4702, which may bethe same as the read/write head 4708, may only be able to detect therelative motion of each track with respect to the specific head 4708dedicated to that multiple track zone 4702. The servo sensing head mayonly be able to determine the total value of the TMh for a particularmultiple track zone 4702. TMh may be a relative motion signal and it maybe used as a feedback signal in the device servo system for eachmultiple track zone 4702 and the device servo system may havepredetermined bandwidth capabilities for the servo performance.

A head transport facility that may use multiple heads 4708 and formultiple track zones 4702 the summation of all TMh's (SUM) may becomputed by the device servo processor to aid the servo system indetermining the TMh and RMh contributions to the total TMh for each headas follows:

Since the LTM 4712 may be the same for all heads, from EQU 1, the sum ofall optical head misregistrations is:

SUM=TM1+TM2+TM3+ . . . +TMN=N*LTM+(RM1+RM2+RM3+ . . . RMN)

Thus to determine LTM:

LTM=SUM/N+(RM1+RM2+RM3+ . . . RMn)/N  EQU 2

The combined RMh may be a non-correlated component for the combined TMhcontribution in the term (RM1+RM2+RM3+ . . . RMn)/N of EQU 2 and it'svalue may be reduced considerably as N increases. Therefore, the LTM4712 value may be approximated by the following equation:

LTM=SUM/N (Approximated)  EQU 3

The LTM 4712 may be an absolute and common value with respect to all theheads 4708 and LTM 4712 may be independent from the motion of theindividual head sensor. The approximated LTM of EQU 3 may be used as aFeed-Forward signal for each head 4708 and multiple track zone 4702servo system to improve the servo error suppression performance for eachhead 4708. The LTM 4712 Feed-Forward signal may be combined with eachindividual optical head 0708 RM signal for improved optical headtracking.

In an embodiment, a method and system may be described for reading,demodulating, and decoding servo information.

Servo track information may be preformatted information on an opticaltape media. This preformatted information may include data and codingsynchronization patterns and track addresses. Servo markings may beplaced on the optical tape media to create a sinusoidal pattern that maybe retrieved from the media by the servo demodulator.

Referring to FIG. 48, an embodiment of phase reversal of a sinusoidalpattern may be shown that may be used to produce a signal encompassing atrack address and data synchronization information.

In an embodiment, the frequency of the sinusoidal may determine thecarrier frequency of the modulation and may provide timing for asynchronous demodulator/decoder. Each eight cycles of the pattern mayrepresent a cell. In an embodiment, any N cycle pattern may be used forthe sinusoidal signal. Each cell may carry information onsynchronization and address bits. A 4-cycle reversal of the phase of thesinusoidal in the cell may indicate a “1-1” bit 4802 that may also be asynchronization pattern bit. The synchronization pattern may signal thebeginning of the address subfields and may be used for synchronization.In the address subfield, the reversal of phase of the two firstsinusoidal cycles in the cell may indicate “1-0” 4804 which may bedecoded as bit “1” for the address and the reversal of phase for thesecond two cycles “0-1” 4808 in the cell may be decoded as bit “0” forthe address.

The decoder may use an analog or digital delay 4810 in order to delaythe detected sinusoidal signal and subtract it from the detected signal.In FIG. 48, the delay 4810 may be shown as a four cycle delay, but thedelay 4810 may be any number of cycles. This may be robust method ofdetecting the reversal of the phase in phase modulated patterns, sinceit may use the shape of the phase shifted sinusoidal itself and not thetiming properties of the pattern.

In addition, a synchronous rectifier 4812, a rest-able integrator 4814,and a level detector 4818 may be used to decode the synchronization andaddress patterns as shown in FIG. 48, FIG. 49, and FIG. 50.

Referring to FIG. 49, an embodiment of an eight bit address field 4902and synchronization bit 4904 are shown. The eight bit address field 4902may be a combination of the reversal of the phase sinusoidal signals asdiscussed in FIG. 48. A “1-0” 4804 may represent a “1” bit 4908 and a“0-1” 4808 signal may represent a “0” bit 4910. The sync bit 4904 maysignal the beginning of the address subfields and may be used forsynchronization.

Referring to FIG. 50, an embodiment of a block diagram of the servodemodulator/decoder 5000 may be shown. The demodulator/decoder 5000 maydemodulate and decode the sinusoidal servo signals into synchronizationand address bit information. The demodulator/decoder 5000 may include adelay filter 5002, a first threshold detector 5004, a PLL 5008, asynchronizer 5010, synchronized rectifier 5012, a synchronizedresettable integrator 5014, and a second threshold detector.

A method for producing tools for creating nickel electroformed shims foroptical tape embossing is disclosed herein. The tools may be also calledPDMS shim fathers.

Referring to FIG. 51, one of a plurality of quartz blank plates 5110 maybe embossed with an embossing pattern 5112 using a hard phase aperturephotomask production etch process 5114, the result being an untreatedmaster 5116. Untreated master 5116 may be treated with one or morehydrophobic coatings 5118 which produce 5120 chemically boundalkylsilicone or polydimethylsiloxane “siliconized” surface master 5122(United Chemical Technologies Glassclad 18 or Glassclad 6C).

A blank quartz plate 5110 may be oxygen plasma cleaned 5124, generatinga cleaned quartz plate 5126. Raw PDMS 5128 (Dow-Corning Sylgard 184 orequivalent) may be degassed 5130, generating degassed PDMS 5132.Degassed PDMS 5132 may be applied to siliconized surface master 5122,and cleaned quartz plate 5126 may be vacuum bagged or pneumatic pressedbonding 5134 against exposed surface of degassed PDMS 5132, resulting inuncured plate stack 5135.

Uncured plate stack 5135 may be then cured on a hot plate 5136. Curedplate stack 5138 may be then separated 5140, resulting in an embossedPDMS film 5142, cured siliconized surface master 5144, and cured quartzplate 5146.

Embossed PDMS film 5142 may be a near zero shrinkage replica of quartzuntreated master 5116, and may be further used to electroform 5148nickel shims (not shown). Embossed PDMS film 5142 has advantages overphotopolymer or photoresist replications that include ease of releasingof the nickel electroformed father and very faithful patternreplication.

A method for producing an electroformed nickel embossing drum using twoor more discrete nickel electroforms is disclosed herein.

Referring to FIG. 52, a plurality of nickel electroforms 5210 may beproduced using a process selected from a set including conventional PVDmastering technology (laser beam recorder), photopolymer fathers, PDMSfathers, and photoresist fathers made from an etched quartz master.

Nickel electroforms 5210 may be precision-cut to align their edges alongthe electroformed format. The cutting may be done with a grindingmachine using a resin bond diamond grinding wheel.

Stainless steel or aluminum perforated shim stock 5230, having apossible thickness ranging from 0.003″ to 0.010″, may be cut toapproximately the nickel electroform width and a multiple of the nickelelectroform length, resulting in a stainless steel or aluminum shim 5230whose length substantially equals the circumference of an embossing drum(not shown).

Shim stock 5230 may be placed on a magnetic chuck on a measuringmicroscope, and may be aligned parallel to the axis of travel of astage.

A first nickel form 5210A may be placed with a leading edge 5215 offsetshim stock 130 and may be held in place by the magnetic chuck, themagnetic force adjusted to permit movement of nickel electroform 5210.Nickel electroform 5210 may be adjusted parallel to the axis of travelof the stage. Full force may be applied to the magnetic chuck to drawnickel electroform 5210 in intimate contact with shim stock 5230, andcryanoacrylate may be used to tack down the edges of nickel electroform5210.

A second nickel electroform 5210B may be placed beside first nickelelectroform 5210A, aligned first nickel electroform 5210A, and tacked inplace. Subsequent nickel electro forms 5210 may be placed beside andaligned to previously placed electroforms 5210 and tacked. This place,align, tack procedure may be repeated until the desired number of nickelelectroforms 5210 may be reached.

Shim stock 5230 with bonded nickel electroforms 5210 may be laser weldedat each electroform seam 5250 that may be perpendicular to the long axisof the shim stock 5230. Leading edge 5215 seam aligning and bonding maybe performed on a convex magnetic chuck having the appropriate radius ofcurvature. Leading edge 5215 seam may be also laser welded on the convexmagnetic chuck.

The assembly may be removed from the magnetic chuck and an innerdiameter seam of shim stock 5230 may be laser welded, and cryanoacrylatemay be applied to all perforations on the inner diameter of theresulting drum.

A roller guide apparatus for transporting optical tape media in anoptical tape system may be herein described.

Referring to FIG. 53, roller shaft 5300 has a large flange 5310 near athreaded end 5320 of center post 5330. Flange 5310 may be preciselymachined such that at least a bottom surface 5315 of raised annulus 5340may be substantially perpendicular center post 5330 long axis. A methodfor ensuring perpendicularity of surface 5315 includes a machiningturning operation. When end 5320 may be inserted into a predetermineddiameter hole in the base plate, surface 5315 of annulus 5340 may bebrought into contact with the base plate surface ensuing roller shaft5300 may be perpendicular to the base plate. Roller shaft 5300 may besecured to the base plate by means of a screw (not shown) that may beinserted into the threaded end 5320.

Flange inner surface 5350 may be flexible under appropriate force. Theflexibility of inner surface 5350 allows precise adjustment of theheight of roller shaft 5310 relative to the base plate. As the screwsecuring roller shaft 100 to the base plate may be further tightened,center post 5330 may be drawn further into the hole in the base plate.With surface 5315 of annulus 5340 resting on the surface of the baseplate, inner surface 5350 flexes, allowing center post 5330 to beadjusted in height while maintaining precise perpendicularity to thebase plate. Flange inner surface 5350 acts as a built-in spring andallows very precise height control, typically better than 1 micron.Factors that contribute to the range of motion and precision ofadjustment include material for roller shaft 5300, diameter of centerpost 5330, thickness of flange inner surface 5350, and screw threadpitch in threaded end 5320.

Referring to FIG. 54, tape damage may be reduced and control may beincreased through application of roller assembly 5400. Roller assembly5400 comprises a roller body 5410, stops 5420, bearings 5430, and rollershaft 5300. In this possible embodiment roller body 5410 may becylindrically shaped and hollow. Roller body 5410 walls may befabricated as thin as possible so as to minimize rotational inertia,resulting in lower lateral tape motion (LTM), reduced tape wear, andfewer tape disturbances.

Stops 5420 may be substantially round disks having a diameter slightlygreater than roller body 5410 and may be assembled to each end of rollerbody 5410. Stops 5420 may be polished to achieve appropriate flatness.Stops 5420 perform the vertical guiding of the tape, may be used toreduce the effects of lateral tape motion, and increase the ability ofthe tape drive to produce dense data recording. Transition area 5440between stops 5420 and roller body 5410 may be a precision 90 degreecorner. The distance between stops 5420 may be designed to be slightlywider (approximately 5 microns) than the width of the tape.

By the nature of the tape, one edge of the tape will run against one ofstops 5420. Thus transition area 5440 where roller body 5410 and stop5420 meet will exert an influence on the tape. The absence of a filletin transition area 5440 allows the tape to remain planar, eliminatingdeformation of the tape. This will increase the life of the edge of thetape, thus preserving the tape drive's ability to control LTM.

Roller bearings 5430, assembled to stops 5420, opposite of roller body5410, provide a smooth bearing surface for the assembly of roller body5410 and stops 5420 to roll smoothly around roller shaft 5300.

Herein described may be a helical transport apparatus and method forusing the helical transport with optical tape media in an optical tapesystem.

Referring to FIG. 55, the possible embodiment of the invention includesa tape transport with a lower reel 5510, an upper reel 5520, wherein atape 5530 can be transported between lower reel 5510 to upper reel 5520.The possible embodiment further includes a plurality of rollers 5540arranged along a substantially helical path 5550 for purposes ofsupporting tape 5530 as it transports between lower reel 5510 and upperreel 5520, effectively causing tape 5530 to spiral in a substantiallyhelical path.

Rollers 5540 may be mounted to a frame (not shown) such that rollers5540 axis of rotation 5560 may be perpendicular to helical path 5550.Lower reel 5510 and upper reel 5520 axis of rotation may be alsosubstantially perpendicular to helical path 5550. The resulting tapepath distance from lower reel 5510 to upper reel 5520 may be dependenton the number of, and spacing of rollers 5540.

In another embodiment of the invention, the number of loops of helicalpath 5550 may be a value greater or less than that shown in FIG. 55.

In another embodiment of the invention, interface heads 5560 may beplaced along helical path 5550 for performing operations such as readinginformation from or writing information to tape 5530. Tape 5530 mayinclude media from a set including optical media, and magnetic media, ormay be of another type. The number and type of head 5560 may be more orless than that shown in FIG. 55.

Referring to FIG. 56, the possible embodiment of FIG. 55 may be shownfrom a top view wherein lower reel 5510 and upper reel 5520 may besubstantially aligned along their axis of rotation. However alternateorientations of lower reel 5510 and upper reel 5520 may be possible inother embodiments.

In another embodiment of the invention, lower reel 5510 and upper reel5520 may be replaced by other means of providing tape 5530 for transportincluding tape manufacturing means, tape format means, and the like.

An adjustable roller guide, as herein described may be used forprecisely adjusting the height of optical tape media in an optical tapesystem.

Referring to FIG. 57, a rotating roller 5710 with magnets 5720 attachedto roller 5710 top and/or bottom surfaces, rolls around a shaft 5730.Roller 5710 may be free to move axially along shaft 5730. A magnet 5740or electromagnetic coil 5750 may be attached to a frame 5770 to whichshaft 5730 may be also attached. At the opposite end of shaft 5730, anelectromagnetic coil 5750 or magnet 5740 may be attached.

In response to a lateral position error signal delivered to coil 5750, acurrent may be applied that changes a magnetic field of coil 5750,causing magnet 5720 (and consequently attached roller 5710) to movealong shaft 5730. The objective of the movement of roller 5710 may be toadjust a tape being guided by roller 5710 to compensate for an unwantedshift in the tape lateral position. As roller 5710 compensates for ashift in tape position, the position error signal may be reduced.

An embodiment of the invention may also be used to adjust roller 5710position to account for tape of differing widths. In an embodiment witha second, stationary roller, roller 5710 can be moved along shaft 5730to “trap” the tape between a top or bottom flange 5760 on roller 5710and a bottom or top flange on the second roller. This embodiment may bewell suited for use with narrow width tapes. Alternatively, for widewidth tapes, roller 5710 can be positioned so that the top or bottomflange 5760 may be coincident with the position of the top or bottomflange of the stationary roller.

In another embodiment with a plurality of rollers 5710, each roller canbe positioned based on the tape width to allow high density tracking.

Writing wobble cycles on a seamless drum, as herein described may beuseful for embossing optical tape media, resulting in an adjustment zonebeneficial to an optical tape system adapted to use the adjustment.

Referring to FIG. 58A, a typical wobble cycle embossing drum 5800,having a center diameter 5850 that may be smaller than an outer edgediameter 5860, results in a varying number of embossed wobble cyclesacross the width of a tape media.

Referring to FIG. 58, a wobble cycle embossing drum 5800 of anembodiment of the invention comprises a drum embossing region 5810, anindex mark 5830, and wobble cycles 5840. Using information selected froma set including embossing drum 5800 maximum diameter and embossing drum5800 minimum diameter, the method of writing wobble cycles 5840 may beadjusted to ensure an adjustment zone 5820 may be present across thelength of an embossing drum 5800.

Referring to FIG. 59, based on embossing drum 5800 diameter along acircumference where each wobble cycle 5910 through 5940 may be written,wobble cycles 5910 through 5940 extend from index mark 5830 around drum5800 and may extend into adjustment zone 5820, but will not extendbeyond adjustment zone 5820, In the possible embodiment of FIG. 59,wobble cycle 5910 extends to a leading edge 5950 of adjustment zone 5820while wobble cycles 5920, 5930, and 5940 all extend into adjustment zone5820

An apparatus, as herein described may provide positional and planarizingsupport for positioning optical tape media under an optical pickup headin an optical tape system.

FIG. 60 shows a possible embodiment of the tape media position andplanarizing support. Support 6010 may include an entry surface 6020, afocus channel 6030, and an exit surface 6040; the entry and exitsurfaces may be substantially elongated truncated cylinder shapes. Thecylinder shapes of the entry surface and exit surface may each have aradius surface; the radius surface may range from 1 mm to 100 mm. Entrysurface 6020 may form a surface on which tape media may slide forpurposes of removing planar perturbations of the tape media. Tape mediamoves substantially perpendicular to the long axis of entry surface6020.

Focus channel 6030 may be a narrow channel separating entry surface 6020from exit surface 6040, forming a possible separation width of betweenapproximately 0.1 mm and approximately 3 mm. The tape media travels overfocus channel 6030 as it moves from entry surface 6020 to exit surface6040 wherein exit surface 6040 may remove planar perturbations of thetape media.

Referring to FIG. 61, an end view of the possible embodiment of theinvention of FIG. 60, focus channel 6030 prevents any minorimperfections in the tape media and/or any minor imperfections in entrysurface 6020, which may disrupt the flatness of the tape media as itpasses over entry surface 6020, from impacting the flatness of the tapemedia as it passes under a tape media read/write head 6110 positionedover focus channel 6030.

Referring to FIG. 61, entry surface 6020 and exit surface 6040 may formdiscontinuous sections of curve, the discontinuity being formed by focuschannel 6030. Such a curve shape for the surfaces may ensure the movingtape media 6120 remains substantially in contact with the planarizingsurfaces. Focus channel 6030 possible width of between approximately 0.1mm and approximately 3 mm, ensures tape media 6120 may be substantiallyflat, traveling in planar form, as it travels under tape mediaread/write head 6110.

FIG. 62 shows an alternate embodiment of the tape media position andplanarizing support apparatus wherein focus channel 6030 longitudinallength may be slightly less than the longitudinal length of either entrysurface 6020 or exit surface 6040.

A reel, as herein described may be used with optical tape media in anoptical tape system to reduce cost and increase speed of optical tapemotion.

Referring to FIG. 63, an embodiment of a single side 6302 of a reel witha plurality of mass reducing openings 6304 may be shown. An embodimentof the invention may include a two piece reel that may produce ahigh-speed and low-cost reel assembly. The flanges of the reel halves6302 may be machined, cast, injected molded, or the like to reduce themass, and thus the inertia of the reel. The reel halves 6302 may be madeof plastic, metal, or other material. The low inertia flanges may allowfor increased acceleration of the reel and may provide for bettercontrol of the tape speed. Additionally, the low inertia flanges mayalso permit the use of smaller motors, since less current may be neededto drive the reel. The use of smaller motors may have a positive impacton power dissipation in the drive. A reduction in power required torotate the reel assembly may provide less heat in the tape area.

In addition to providing low inertia characteristics, the mass reductionopenings 6304 may also create bleed holes for the air to enter and exitthe reel with the media during the winding process. The air entering andexiting the reel with the media may promote even stacking of the mediaon the reel; this may positively impact lateral tape motion. The massreduction openings 6304 may also provide a monitoring technique formedia stacking on the reel. As the media may be stacked onto the reel,there may be a tendency for the media to stack unevenly on the reel. Ifthere may be uneven stacking, there may occur a shift of the tapeposition through the tape path that may reduce the tracking accuracy ofthe closed-loop servo system of the head transport facility.

The mass reduction openings 6304 may allow a monitoring technique to beused to identify if the media may be stacking evenly. A visual methodmay be used to see if the media has stacked correctly. The media stackmay be sensed by a tape drive sensor such as an optical sensor topredict when an uneven stack may occur; this information may be feed tothe closed-loop servo system that may compensate for the tape positionchange.

In an embodiment, this reel design may also have the capability ofproviding positive and negative pressure conditions in the drive area.The positive pressure may be used to cool the electronics in the driveor may create an air film between the tape layers when the tape may bebeing wound. The negative pressure may be used to draw air out from themedia when the reel may be being unwound.

Referring to FIG. 64, an embodiment of the reel assembly 6402 may beshown. In an embodiment, the two reel halves 6302 may be joined byscrews, bolts, fasteners, mechanical connection, friction fit, adhesive,or the like.

In an embodiment, the mass reduction openings 6304 of the two halves6302 may be aligned from the first half to the second half.

In an embodiment, the mass reduction openings 6304 of the two halves6302 may not be aligned from the first half to the second half.

A stamper strip and a process resulting in precise alignment across aseam of the stamper strip, as herein described, may be used to generateoptical tape media with precision tracking alignment.

Referring to FIG. 65, an embodiment of a drum assembly 6500 forembossing information onto an optical tape may be shown. One or more thestamper shims 6504 containing the embossing information in the form of afine surface relief pattern may be wrapped around a drum base 6502. Inan embodiment, the stamper shim 6504 may be held in place by a magneticforce, a mechanical connection, an adhesive connection, or the like.

In an embodiment, the drum base 6502 may be magnetic and the outersurface may be polished optically smooth. The drum base 6502 may be madeof a magnetic material, may be non-magnetic and have an outer layer ofmagnetic material; the outer layer may be a magnetic coating applied todrum base 6502. The stamper shim 6504 material may be a paramagneticmaterial such as nickel or Nichrome that may allow stamper shim 6504 tomagnetically attach to drum base 6502 surface. In another embodiment, anon-magnetic stamper shim 6504 may be bonded to a paramagnetic materialsuch as nickel or Nichrome to permit attachment of bonded stamper shim6504 to magnetic drum base 6502.

In embodiment, the drum base 6502 may be made of a paramagnetic materialsuch as nickel or Nichrome or may have an outer layer of paramagneticmaterial; the outer layer may be a paramagnetic coating applied to drumbase 6502. The stamping shim 6504 may be a magnetic material. In anotherembodiment, the stamping shim 6504 may be made of a non-magneticmaterial with a bonded magnetic material to permit attachment of bondedstamper shim 6504 to paramagnetic drum base 6502.

In an embodiment, the stamper shim 6504 may be further held in place todrum base 6502 using an adhesive through glue holes 6508 in the drumbase 6502 after alignment has been achieved.

Embossing features, that may be used to provide a format to the opticaltape, may be on the outer surface or outer diameter of the stamper shim6504. At least one stamper shim 6504 may be used to provide one completeset of tracks around the outer diameter of drum base 6502. With the atleast one stamper shim 6504 applied around drum base 6502, at least oneseam will be formed where the stamper shim 6504 ends meet. It may beimportant for the corresponding tracks to align accurately across theseam and/or seams. A plurality of stamper shims 6504 may be used aroundthe circumference of the drum base 6502 for practical and manufacturingreasons. In embodiments, when multiple stamper shims 6504 may be wrappedaround the drum base 6502, accurate alignment of the tracks across themultiple seams may be required.

In an embodiment, the stamper strip 6504 and the drum base 6502 may beattached by magnetic force and it may be relatively easy to laterallyadjust the stamper shim 6504 ends on the drum base 6502 to align thestamper shim ends.

Referring to FIG. 66, an embodiment of a stamper shim 6504 alignmentmethod using differential screws 6602 may be shown. In an embodiment,this alignment method may include a course adjustment followed by a fineadjustment of the stamper shims 6504.

In the coarse alignment step, a microscope such as a stereo microscopemay be used to focus on the seam 6604 area of the stamper shims 6504.While viewing through the microscope, the stamper shims 6504 tracks maybe aligned to within approximately +/−10 microns. Fiducial marks alongthe outer tracks and in between tracks may be used for this coarsealignment.

After the coarse alignment has been completed for all the stamper shim6504 seams 6604, a fine alignment step may be performed for the finalalignment of the embossing features.

In this step, the drum may be mounted on a spindle and rotated at arelatively slow rotational speed. This step may be accomplished using anoptical media tester such as a Shibu Soku machine. An optical pickuphead on the tester may focus on the surface features of the stampingshim 6504. The optical pickup head may focus and lock onto a track, mayread the track, and may decode the track address. The optical pickuphead may perform this process for the tracks on both sides of the seam.Electronic circuitry may be designed to accommodate the presence of thestamper seam 6604. Once the track addresses are determined for thetracks on both sides of the stamper shim 6504 seam 6604, the track maybe aligned. For a drum with multiple shims, the alignment of each pairof stamper shims 6504 seam 6604 may be adjusted laterally with theprocess described above for each pair of stamper shims 6504 seam untilthe tracks are aligned.

Continuing to refer to FIG. 66, a first embodiment of a stamper shim6504 fine adjustment using differential gauges may be shown. At leastone differential gauge 6602 may be mounted on the rim of drum base 6502;the differential gauge 6602 may have micron level adjustment capability.The first differential gauge 6602 may be used to push the stamper shim6504 in one direction. A second differential gauge 6602 may be mountedon the opposite side to push the stamper shim 6504 in the oppositedirection. In this manner, the stamper shim 6504 may be adjusted withmicron precision in either direction to align the tracks of the stampershim 6504. There may be at least one differential gauge 6602 at eachstamper shim 6504 seam. The process of course and fine adjustment may berepeated for each seam due to a pair of stamper shims 6504 of drumassembly 6500. At least one differential gauge 6602 may be driven byelectronic feedback from the pickup head as described above.

Referring to FIG. 67, a second embodiment of fine adjustment using apiezoelectric transducer 6702 to align the stamper shim 6504 seams 6604may be shown. At least one piezoelectric transducer 6702 may be placedbetween the drum base 6502 and the stamper shim 6502 at each seam 6604.Using the at least one piezoelectric transducer 6702, the process may beautomated by providing an electronic feedback loop where the alignmentinformation may be obtained by the media tester and may be used to drivethe piezoelectric transducer 6702 to align the stamper shim 6504.

An automated closed loop system may be developed by using a pickup head6704 to read stamper shim 6504 tracks and feed the track informationinto a processor 6708. The processor 6708 may be a microprocessor,microcomputer, microcontroller, or the like. The processor 6708 maycontain memory for storing the stamper shim 6504 track positioninformation. The processor 6708 may also be able to provide feedback topiezoelectric transducers 6702 for alignment of the stamper shim 6502.The close loop system may also include an amplifier 6710 to provide theproper signal level for piezoelectric transducer 6702.

The pickup head 6704 may be allowed to move across all the tracks of thestamper shims 6504 to determine the track alignment. As the drumassembly 6500 may be slowly rotated around a center axis, the pickuphead 6704 may read and send adjustment signals through the processor6708 to at least one of piezoelectric transducers 6702 to align thetrack of the stamper shim 6504. The drum assembly 6500 may be rotatedone or more revolutions to align the tracks across the stamper shims6504.

In an embodiment, after a first pair of stamper shims 6504 across a seamare aligned, the pickup head of the close loop system may move to asecond pair of stamper shims 6504 to achieve alignment. In anembodiment, the pickup head 6704 may align all of the shims of the drumassembly 6500.

In an embodiment, the close loop system may use an average of allstamper shim 6504 tracks to provide alignment to all the tracks.

In an embodiment, the close loop system may require perfect alignment ofseveral given tracks for all the shims 6504 around the entire drumperimeter.

A testing apparatus, as described herein may be useful for testingvarious aspects of optical tape media.

Referring to FIG. 68, a cylindrical drum 6810 may be mounted onto arotating shaft 6820. In turn shaft 6820 may be coupled to a motor (notshown) which can be remotely controlled to rotate at various desiredspeeds. The motor may be assembled to a firm base 6830. A length ofmedia 6840, with predetermined features of formatting information, inthe form of a continuous loop may be secured to the outside of drum6810. An optical head 6850 may be positioned at a close distance abovemedia 6840, within focus range of head 6850. The alignment of head 6850to a surface of media 6840 may be effected by a mechanical adjustmentmeans 6860.

When energized, drum 6810 rotates at a desired speed, and head 6850reads the features on media 6840, transferring any information read fromthese features to a computer (not shown) for analysis. One such analysisthat can be performed may be a measure of quality of the media.

An adapted optical tape drive, when combined with an optical mediatester, results in a test system, as described herein that may be usefulfor testing optical tape media in a configuration substantially similarto that found in an optical tape system.

Referring to FIG. 69, a tape drive 6910 may be adapted to present media6920 to an optical media tester 6930 horizontally. In this possibleembodiment, optical head 6940 of optical media tester 6930 may beoriented vertically, impinging on media 6920 bottom surface.

Optical head 6940 includes functions selected from a set includingfocus, tracking servo, and data interpretation. Information collectedfrom optical head 6940 while performing one or more of the functions,may be analyzed to assess factors selected from a set including, lateraltape motion, tension variation, tape surface defects, andcharacteristics that exist in tape drives such as non-uniformities inthe reels 6950, rollers 6960, and tape servo system (not shown).

An aligned, seamed, embossing drum and a process for production thereof,as herein described may be used to emboss optical tape media.

Referring to FIG. 70, a hollow, modified vacuum chucking drum 7010fabricated from Pyrex or other suitable glasses to hold a plurality ofshims 7015 around its outer diameter with a wall thickness ofapproximately 0.5 inches. In this possible embodiment of chucking drum7010, through-holes 7020 may be formed through a wall of drum 7010 foradhesive dispensing to adhere a precision cut, etched, polycarbonateshim 7015 to drum 7010 outer surface. In this possible embodiment, shim7015 may be approximately 100 micron thick; however other appropriatethickness of polycarbonate may be used. Shim 7015 may be first cut to apredetermined size for fitting onto drum 7010 from a larger sheet usinga cutting method selected from a set including diamond fly cutting,water jet cutting, and diamond wheel grinding. The larger sheet may beetched from a quartz backed photopolymer which may be first producedfrom a quartz etched master.

In other embodiments, distribution channels 7030 along chucking drum7010 outer surface may be included for disbursing adhesive from throughholes 7020. Alternatively, through holes 7020 may be omitted anddistribution channels 7030 may be included, extending to either end ofdrum 7010 for adhesive application.

Adhesive applied via through holes 7020 and/or distribution channels7030 may be approximately a UV curable adhesive. However other types ofadhesive may be used.

Referring further to FIG. 70, drum 7010 includes vacuum channels 7040and vacuum ports 7050 working cooperatively to allow a drum vacuum (notshown) to interface through vacuum end cap 7060 to cause vacuumingaction through vacuum ports 7050 to temporarily hold shim 7015 in placeduring adjustment and adhesive curing.

Referring to FIG. 71, one or more shims 7015, roughly aligned to end cap7070 and held in place by vacuum ports 7050, may be checked foralignment using an optical means. Vacuum through vacuum ports 7050 maybe modulated to allow micrometer-like movement of shims 7015 along drum7010 outer surface for final alignment. Adhesive (not shown) may beintroduced through either through holes 7020 and/or distributionchannels 7030, inspected, and cured. Inspection of adhesive may beperformed through shim 7015 or through drum 7010 if the drum may betransparent (such as Pyrex).

Referring to FIG. 72, completed drum assembly 7210 may be mounted on aweb embosser (not shown), with a UV lamp 7220 inserted in drum 7210,with appropriate shielding 7230. This allows exposing UV embossingmonomer (7240) without having to pass UV light through tape base 7250.

In another embodiment of the invention the hollow, modified vacuumchucking drum 7010 can be fabricated from metal. This requires UV lamp7220 be mounted outside completed drum assembly 7210 such that UV lightpasses through tape base 7250.

In another embodiment of the invention, vacuum modulation and controlmay be controllable for each shim individually, allowing none, one, orany plurality of shims to be adjusted simultaneously prior to adhesivecuring.

A process herein disclosed improves performance of multilayer opticalmedia (e.g. optical tape) including a monomer layer on a substratelayer. The process disclosed for monomer curing includes exposure of themonomer to ultraviolet light. The process may improve performance byincreasing adhesion of the monomer to a substrate, increasing cohesionwithin the cured monomer, and decreasing tackiness of the exposedsurface of the cured monomer.

Referring to FIG. 73, the process includes exposing the monomer to abroad spectrum ultraviolet light after a delaminating step. First curingstep 7310 may use ultraviolet light from light emitting diodes. Firstcuring step 7310 may be performed while the media may be still on anembossing drum, and may be beneficial in that it minimizes the heatinput to the thin substrate of the media during embossing. Usingultraviolet light from light emitting diodes also may eliminate heat upof the embossing drum so there would be no need for drum cooling.

In embodiments use of a broader band ultraviolet energy source mayprovide a broader foundation for monomer curing in first curing step7310 while possibly increasing temperature of the media and embossingdrum.

Referring to FIG. 73, the media may be delaminated in delaminating step7320.

Referring to FIG. 73, post delaminating curing step 7330 may include useof a broad spectrum ultraviolet light, ultraviolet light from lightemitting diodes, or a combination thereof. The combination thereof mayreduce media deformation risk from excessive heating with a broadspectrum ultraviolet light alone.

(I) Mod2 Embosser

Substrate Tracking

Alignment of machine has been demonstrated beneficial for facilitatingproper web tracking of both 2 mils and 6 micron PEN.

Coated idler roll surfaces may reduce friction and facilitate improvedweb tracking resulting in fewer creases. For example:

PTFE, Ni-impregnated Teflon on metal and plastic was found toeffectively reduce friction in our systems; and

TFE coated of Embossing tools (Ni electroforms and Hg'x) may facilitateimproved release.

Sequencing of the drive system while Operating Mod2 with 6 micronsubstrate may facilitate avoiding web breaks. For example:

Setting and engaging web tension prior to driving the web; and

Setpoints for the sections of the machine may include:

Main drive set at 26 rpm (resulting in virtually no web movement, butthe motor may be engaged);

Motor 3 Rewind tension set at 1 lb;

Motor 4 Unwind tension set at 0.6 lb;

After tension may be set, rewind tension may be raised in 0.5-0.75increments up to 2.5 lbs;

Unwind tension may be raised to 0.65-1 lb; and

After tensions may be at aim, main drive line speed can be increased in1-2 rpm increments

Sequencing of the drive while Operating Mod2 with 2 mils substrate mayfacilitate avoiding overload of motors. For example:

Setting and engaging web tension prior to driving the web; and

Setpoints for the sections of the machine include:

Main drive set at 26 rpm (resulting in virtually no web movement, butthe motor may be engaged);

Motor 3 Rewind tension set at 1 lb;

Motor 4 Unwind tension set at 1 lb;

After tension may be set, rewind tension may be raised in 0.5-0.75increments up to 3.5-4 lbs;

Unwind tension may be raised to 2-3 lbs; and

After tensions may be at aim, main drive line speed can be increased in1-2 rpm increments.

Sufficiently high rewind tension may facilitate quick machine recoveryfrom temporary perturbations in tension such as those caused by engagingnip rolls.

The above sequencing and operating responses may be built into thecontrol system logic reducing the possibility of operator error duringmachine operation.

Edge Guides

Unwind edge guide control system may be modified to facilitate dampenedresponse time and reduced creasing which may be due to rapid andexcessive changes in the magnitude of the unwind positioning system.

Rewind edge guide control system may be modified to facilitate dampenedresponse time and reduced creasing which may be due to rapid andexcessive changes in the magnitude of the unwind positioning system.

Rewind edge guide may be mounted on the moving mechanism of the motor(lateral motion) which may facilitate ensuring that the edge guide maybe controlling to the edge of the winding roll, rather than to thebackplane of Mod2. This may allow improved uniformity of the edge of thewinding roll, which may be likely to be important for the subsequentvacuum coating processes.

Corona Treating

For the monomers tested on Mod2 a power level of 0.75 kw appears toprovide good adhesion, assuming that the curing of the monomer may besufficient. This process window was defined by corona treatingsubstrate, cutting out a stop-action sample, and manually laminating thesample with monomer and curing in the Oriel lamp system for 3 minutes(known to be a sufficient curing level).

For a power level>0.75 kw, measured surface energy of the substrate ˜54dynes.

Monomer Coating

Monomer coating using a manual syringe may be adequate for preliminarytesting of the embossing process. At a web speed ˜6 fpm, a sinusoidalpattern of droplets on the web at a frequency of ˜1 drop/sec may providea sufficient supply of monomer to the embossing process to yield agenerally cross-web embossed CD pattern (with the CD drum). Asignificantly lower supply of monomer may reduce cross-web coverage. Ahigher supply of monomer may result in squeeze out from the edges of thedrum.

As an example, a coating application technique using anAnilox-to-rubber-to-web was found to produce well-controlled, uniformcoatings.

Substrate Anti-Stat Protection

Use of anti-stat devices, may facilitate avoiding poor performanceareas. For example improvements using anti-stat devices may include:

Web tracking may be improved for 6 micron PEN; and

Droplets may be better formed on the web surface coating of monomer whenusing a syringe.

The above may be achieved with the use of Po-210 nuclear antistat barsat 4 locations. The possible locations include:

Post-unwind

Post-corona treat unit

Post-embossing

Pre-rewind

Electrostatic antistat bars were also evaluated and found to work aseffectively (in addition to presenting a shock hazard) as nuclear bars.

Embossing Process and Equipment

A nip pressure of at least 15 psi may provide sufficient force to resultin good lamination using the CD drum.

Use of a single nip roll (infeed only) appears to allow a higher tensionoperating point on the embossing drum. This may be a result of

Less isolation from the rewind tension level set

Inertia in nip roll #2, the impact of which may be exacerbated when theroll in engaged

Use of two nip rolls (infeed and exit) macroscopically results inacceptable operation. Some examples include:

Use of a seamed drum with regular seams may facilitate monitor evennessand ease of flow;

Engaging the two nip rolls with a good match of pressure facilitatestracking; and

A better controlled release point of the web from the drum; i.e., withthe exit nip roll engaged, the web's drum release point may be “pinned”better due the pressure on the web from the closed nip roll.

The following input nip roller characteristics may be beneficial forthin webs: durometer (harder may be better), surface finish (pattern canprint through backside of thin film, and diameter (larger diameterimparts less differential tension to infeed web).

Lamination Process Control

Precise Side-to-side lamination control of nip pressure may facilitatelamination.

Curing Process and Equipment

Equivalent degree of curing was found within the operating range ofseveral different curing systems, for example:

Oriel “solar simulator” which may be a broad spectrum system;

The “belt UV system” which may be a broad spectrum system;

The Xenon flash lamp system; and

Infinilux & UVPS UV LEDs, which output a narrow wavelength lightdistribution centered at 395 nm.

For all of the above systems, good curing was found at some combinationof light intensity setting and exposure time. Using certain monomerformulations may facilitate further good curing.

For the lamp systems, there may be a well defined curing “position” forthe substrate which may be based at least on focal point or uniformexposure point of the lamp system

For the LED system, UV intensity was measured across the LED “tripletstrips” at distances of ½″ and 1″ from the surface of the strip. It wasfound that a relatively uniform energy profile exists at a distance of1″ from the strip; at the ½″ distance, a significant variation ofintensity was measured with a large drop between the LED sources

For the Oriel system, using a possible monomer such as ACT2-158-1, goodcuring was observed with exposure times as low as 5 seconds or less.

The above exposure process operating point may be important, because theMod2 exposure time using the 4″ diameter CD drum, with the placement ofthe UV LEDs on the unit, may be on the order of 3 seconds (approximately2 inch exposure window at 6 fpm).

Substrate Rewinding

Substrate rewinding may be affected by surface roughness of the web (alow level of roughness may be incorporated by the substratemanufacturer, generally) to enable some air entrainment and may reducesurface friction and wrinkling at the windup.

By proper set up of the machine (either Mod2 or the Mill Lane; alignmentand operating parameters), may facilitate good rolls of substrate beingcompleted (i.e. roll may be “hard”, well formed, and has minimalwrinkling; at least as good as incoming substrate).

Web rewinding quality may vary depending on the processing conditions.Note that all of the conditions below utilize no special equipment toassist rewinding (i.e. lay-on rolls or bowed spreader rolls):

2 mils PEN without coating yielded a good roll

6 micron PEN without coating yielded a good roll

2 mils PEN coated with polymer (cured monomer) using a uniform drumwithout seams yielded a good roll

2 mils PEN coated with polymer (cured monomer) using a patterned drumwith seams yielded significant air entrapment in the area of the seam;probably due to excessive level of tackiness in areas where the monomercoating was thicker due to the seams and undercured at these locations.Manifestation was in “bubbled TD areas on the winding roll” whichsubsequently caused creasing.

6 micron PEN with polymer (cured monomer) using a uniform drum withoutseams yielded significant creasing in the winding roll coincident withthe polymer coated surface contacting the backside surface on thesubstrate on the rewind.

6 micron PEN with polymer (cured monomer) using a patterned drum withseams yielded significant creasing in the winding roll coincident withthe polymer coated surface contacting the backside surface on thesubstrate on the rewind The bubbling seen with 2 mils PEN appears to beoverwhelmed by the creasing problem, or may be simply not present due tothe lower beam strength of the thin substrate passing through laminationnip.

Very uniform x-web tension at the rewind may facilitate high qualityresults when using thin films.

(II) Vacuum Coater

Pilot Roll Coater

Designed and installed new web transport/guide assy featuringbackside-only idler and bowed (stretcher) rolls for optimization of thinweb handling.

Improved software machine controls

Upgraded deposition capability for 4 tandem sputter targets (2 DC & 2 RFmagnetron) to allow doubling the SiO2/ZnS deposition rate.

Designed and implemented in-line reflectance measuring capability basedon use of fiber-optic height sensor configured to measure reflectance.One bank of each linear array can be situated between each depositionzone.

Developed hardware to modify degree of isolation between each depositionzone to control interlayer mixing.

Pilot Batch Coater (Sharon)

Installed spiral wrap device to allow coating of discrete lengths oftape

Added “auto-indexer” to precisely rotate substrate holder over targetsMonomer materials:

Monomer formulations were developed by several custom formulationsuppliers to predetermined specifications and characteristics. Keyparameters specified included:

Spectral sensitivity (for curing through PEN film);

Viscosity (aim may be low for good flow-out during the embossingprocess) such that low viscosity generally results may be lower chemicalresistance

Temperature modulation was identified as a method of controllingviscosity (hence embossed layer thickness);

Curing rate (aim may be fast to increase process throughput);

Adhesion to plastic (for some Micon programs);

Low-adhesion to plastic (for other Micon programs); and

Release from “nickel tooling” for all Micon programs (assuming Nitooling in the future).

Surface treatment (and volumetric treatment in the case of polymerictools) were found to reduce the adhesion between the tool and thereplication polymer.

Preliminary testing has occurred using a silicone release agent toimprove separation of the cured monomer from the tooling surface. Inaddition, the release additive may be intended to provide some slipbetween the surface of the cured monomer and the backside of the webduring rewinding (see rewinding section).

Monomer formulations which were sensitized into the blue region of thespectrum may be highly reactive and avoiding exposure to room lightingmay be possible. This may be generally accomplished with the syringedispensing method by wrapping the syringe with tape (e.g. Kapton tape)to filter the ambient blue light. This avoids the complexity of usingentirely closed fluid handling systems.

Polymer Adhesion:

Polymer adhesion may be modified by several influences, including:

Intrinsic adhesion of the cured monomer to various surfaces;

Substrate treatment (note that both corona and flame treatment have beenshown to improve adhesion); and

Substrate sub-coating with adhesion promoting layers (adhesion promotingsub-coats displayed improvement in most cases, but in some testing,there was no impact).

Vacuum-Deposited Layers:

WORM layer recipe used Al and Sb as first layer

Alloy layer used Ge2Sb2Te5 nominal alloy

Overcoat used ZnS/SiO2 layer

Thicknesses of each layer varied for optimum performance

Using a vacuum-deposited layer as backside anti-static coating wasevaluated using Al; preliminary test result in tape transport werepositive

Discreet Tooling:

As a near-term achievable alternative to developing a seamless drum forOT preformatting, a process was used which includes the precisionpre-cutting of multiple Ni electroforms (“shims”) having the desiredpre-format pattern and laser welding the individual segments into adrum.

Original format designs were created (via standard CAD processes) and anoriginal relief representation (“master”) was made by patterning a glasssubstrate using lithographic techniques.

Fiducial cutting marks were included in the CAD pattern for later use inprecision cutting of the pattern tooling.

Polymer-on-glass submasters were made directly from the master.

Reverse-image submasters (“mothers”) were also made from the submaster.

Ni electroforms were made from polymer submasters

Submasters may also be made from master

One or more of the following methods may achieve clean separation aftera vacuum deposition process such as sputtering 40-70 nm of NiV, themethod include:

Additional treatment of the polymer submasters to increase hardness;

Additional treatment of the polymer submasters to reduce adhesion topolymer surface;

Use thinner NiV layer;

Ramp sputter power to reduce temperature of initial deposit; and

Passivate NiV (as may be dome during Ni-to-Ni replication).

Both the polymer submasters and Ni masters were used as discreet flatshims in producing test replicas of the preformat pattern by a UVprocess which includes:

Flat lamination through pressure rollers at 50-75 psi with UV curingfluid [described previously] injected at point of lamination (“nip”);and

Cure by UV or optical radiation (4 sec to 6 min); 2-200 mw/cm2.

Drum Tool Fabrication:

Flat Ni shims were precision mill cut (“trimmed”) using carbide cuttingtools based on pre-determined distance from fiducial marks embedded inNi shim enabling four virtually identical shims to be made by thistechnique. Also a plastic protective film was laminated to patternedsurface of Ni shim, and peeled back temporarily to view fiducial marksprior to trimming

Laser welding was used to join the 4 shims into a drum

All 4 shims were aligned to one (bottom) edge and 3 welds were made fromthe back side, ˜75% through the Ni, then the welded strip was flippedover and the finish weld was made from the front (patterned) side

The final weld to form (close) the drum was made through the front side

Optical measurements showed the highest weld precision (least offset ofone track across the welded seam) was 0.00015 inches (3.7 microns) forthe first drum processed by this method.

It was determined that a set of custom welding fixtures and additionaltesting may facilitate further reducing the offsets and improve thesmoothness of the welding process.

Installation and Operation in Mod2:

Substitute Ni drums with CD patterns were installed in the Mod2 forpreliminary process and machine testing [see above]. The drum wasfixtured into the machine by sliding it over a rubber sleeve, which inturn was slid over the machine's drive shaft and was secured bycompression of an end bell by use of a nut on the end of the threadeddrive shaft.

Product application may include

¼, ½, ¾, 1, 4″ inch tape width

Possible may be ½″

Referring to FIG. 74

Top reading version (laser incident on “topcoat” side):

7410 Topcoat

Organic cured layer

PML (vac polymer deposition—acrylic) planarization

UV cure

EBeam cure

Solvent/aqueous coating

Purpose may be to protect the structure

Optical properties

7420 WORM Layer #3 (a.k.a. “Topcoat 1”)

An optional layer as part of the stack

Protects during manufacturing

Provides some optical tuning

Possibly (ZnS/SiO2, 80/20); alternates are SiO2, YF2, other transparentoxides and compounds

Thermal properties

Optical properties (T, R, A)

Flexibility

Adhesion (high)

Surface roughness

7430 & 7440 WORM layers

Possible may be Te alloy (GST=Ge2Sb2Te5 nom)

Metal (possible may be Sb, Al)

Thickness depends on product performance

7450 Pre-format layer

Possible may be UV cured polymer

Possible may be acrylic (possible epoxy or polyurethane)

Possible may be Viscosity (<200)

Possible may be Spectral sensitization (400 nm)

Possible may be Adhesion to substrate (high)

Possible may be Adhesion to tooling (low)

Possible may be Flexibility (high)

Layer thickness (0.5-1 u)

Preformat layer formation processes (options: single or multi-stepsequence)

7460 Substrate

Materials

Possible may be PEN

PET

PC

CTA (cellulose triacetate)

Thickness

1 u-25 u (possible ˜4-8 u) Possible may be 6 u

Other properties

Surface roughness

Subcoats

Fillers

Heat stabilization

Mechanically balanced stress

Surface treatment and or chemical treatment

7470 Backcoat(s)

Surface roughness

Optical properties

Possible may be Antistatic

Anti-stiction

Possible may be thin metal layer (Al, Ni, NiCr)

Carbon black may be alternate backcoat (as standard industry practice atthis time)

(Anti-Curl Layer as Option)

Texturizing by embossing or formulation and additives (particulates) ordrying

Purposeful reticulation

Other considerations:

Possible may be Write dark and light (final tbd)

Tuning of chemistry to the correct write wavelength

Texturing of surfaces for improved drive performance

A second version exists may be read from the other side

Backcoat

Topcoat (?)

WORM layers

Pre-format layer

Substrate

Topcoat

Clear, protective

Texture control

Transparent (to R/W wavelength)

Antistat

WORM to R/W

May have erasable capability

Possible may be phase change

Possible may be pre-formatted layer in the structure

A seamed drum with a restart zone, zeroing zone, and the like, plus amethod for forming the seamed drum

The following description refers to several possible embodiments of thedisclosure and it may be understood that the variations of theembodiments and methods described herein may be envisioned by oneskilled in the art, and such variations and improvements are intended tofall within the scope of the disclosure and therefore the disclosure andmethods are not limited to the following embodiments.

FIGS. 75 through 78 show the current art and illustrate how nonuniformcoatings result from non-uniform source distributions. The subsequentfigures illustrate how the method of this disclosure, which utilizes aspiral path and multiple passes through the source, has the effect ofimproving the uniformity of the coating.

In a typical configuration, shown both in FIG. 75 in side view, and FIG.76 in normal perspective view, the substrate 1 to be coated, herein alsoreferred to by convention as the web, may be feed from a supply spool 2,and after passing over additional roll 3 to control tension andpositioning, etc., the substrate enters coating zone 5, which includessource 6 from which material for the first layer 7 may be deposited, andcoating barriers 8 to minimize overcoating of excess material from thesource. Additional materials may be deposited at sequentially locatedcoating zones (not shown), after the last of which the coated substrate,after passing over additional tensioning and positioning roll 4, may betaken up on re-wind spool 12. In this known art, the substrate traversesthe coating zone in an essentially linear direction, and the web may beeither a free span, i.e., unsupported on the back side, or in contactwith a backing plate 13 or roll which may be typically used to cause theweb to lie flat and/or to remove excess heat from the depositionprocess. In the latter case, the backing plate or roll can optionally becooled.

In the figures of this disclosure, motors, speed control elements,tension controls, web guides and the like are not shown in the figuresof this disclosure for clarity, but such control systems are well knownto the art (D. R. Roisum, The Mechanics of Rollers, TAPPI Press,Atlanta, 1996).

Now referring to FIG. 77, a general schematic of practice common to theart may be given of the cross-section of a substrate during the vacuumdeposition process, as viewed in the machine direction. This diagramshows one example in which a nonuniform deposition of material 19 arisesfrom a non-uniform flux distribution 17 from the source, where crucible15 filled with material 16 may be evaporated (for example, by means ofresistively heating crucible, not shown). The flux, typically describedas the mass or thickness of material being evaporated per unit time, maybe shown graphically as distribution 17, where the highest rate ofevaporation may be represented by the longest arrow (at the center inthis example). Material 19 generally condenses on substrate 18 inproportion to the flux distribution, and may be thus distributed asmaterial layer 19, with the thickness being approximately proportionalto flux 17.

FIG. 78 represents the normal-incidence view of a non-uniform coatingsimilar to that of FIG. 77 that can result from a non-uniform fluxdistribution. Here, unwind spool 24 supplies substrate 25 to coatingzone 26 over guide/tension/idler rollers (represented here by 27).Material 30 may be evaporated from crucible 28, with deposition shields29 minimizing stray coating. The coated substrate 31 travels overadditional guide/tension/idler rollers (represented here by 32) and maybe rewound on take-up spool 34. The horizontal dotted lines 35 indicatehypothetical slitting locations if this substrate were ultimately to bemade into a tape product. Variations in coating thickness 36 may be theresult of the non-uniform flux from crucible, as shown previously (FIG.77).

FIG. 79 shows a schematic diagram of one embodiment of the presentdisclosure in which a tape-like substrate 41 (typically a polyethyleneterephthalate, PET, or -naphthalate, PEN, or polyimide film or the like)may be supplied by unwind spool 40 to a web guide, tension controlroller, and additional idler rolls (not shown for clarity), over roll42, then to roll 43, and then enters coating zone of deposition sourcematerial 45, then to roll 42 and back to 43, etc. following anessentially spiral pathway and traversing the coating source 45 a numberof times before exiting the coating zone and rewinding on spool 47. Theeffect of multiple passes through various parts of source 45 may be toaverage out the coating thickness non-uniformities resulting from anonuniform flux (as, for example, shown in FIG. 78). It should be notedthat in this drawing the wraps of tape around rolls 42 and 43 are widelyseparated for purposes of illustration only, and would be close togetherin an actual coating configuration. It will be noted that a line speedincrease will be in proportion to the tape width decrease will maintainan equivalent deposit thickness and throughput for the tape relative toa conventional (full width) coating configuration. Since the method ofthis disclosure offers increased immunity to source variations resultingfrom higher flux rates, further speed increases may be also possible.

In order to reduce the heat load from the deposition process, rollers42/43 in FIG. 79 can also be cooled, by circulation of coolant, etc. Thehigher linear tape speed and lower deposition rate per pass, incombination with the 180 degree wrap angle of [optionally-chilled] rolls42/43 between coating passes, will act to reduce the thermal load on thetape from the deposition process.

The beneficial effects of the multi-pass averaging technique of thisdisclosure can be seen by examining the diagram in FIG. 80. Brieflyreferring back to FIG. 77, the substrate 18 of that figure has now beenreplaced by a narrow width substrate, denoted by 57 in FIG. 80.Following the tape path shown in FIG. 79, tape substrate 57 in thisexample makes 8 consecutive traverses through coating zone 50, havingmaterial flux emanating from crucible 51 (with the source also havingthe same non-uniform flux distribution 52 as FIG. 77), where thesuccessive passes of substrate 57 may be denoted by positions 1 through8 (note: the upper traverses of the complete tape path have beeneliminated for clarity). The coating layer build-up 54 through 55 may beexaggerated to illustrate the averaging effect. The multiple-passaveraging effect may be compared to the coating material from the samemodel source distribution in FIG. 77, where no multiple-pass averaginghas taken place, after slitting.

It can be appreciated from this illustration that improvement inuniformity may be achieved from most source configurations, since theaveraging effect may be based on the width of the substrate being smallcompared to the width of the source, and multiple passes sample manysections of the material source distribution.

In another embodiment, shown in FIG. 81, the single rollers 42 and 43 ofFIG. 79 have been replaced by multiple individual guide rollers 60 and61 in order to more precisely guide the tape. This could also beachieved by cutting guide track grooves into rollers 42 and 43. Again,in actual operation, the individual wraps would be close together formaximum uniformity and yield.

It may be also a feature of this disclosure that a means for collectingexcess (“stray”) material from the source may be provided, as shown inFIG. 82. It may be an undesired characteristic of most vacuum coatingsources, including e-beam and thermal evaporators, that excess materialform the source can be deposited in areas other than the substrate, andthis not only requires periodic cleaning, but can interfere with thecoating operation when such unwanted deposition occurs on rollers orguides and thereby changes these surfaces and alters the performance ofthese devices. Also, excess material can contaminate other coatings,either by flaking off of surfaces where a substantial buildup ofmaterial exists, or by re-evaporating from heated surfaces. In theembodiment shown in FIG. 82, which may be a side view of the method ofFIG. 79 or 6, the tape substrate 73 may be unwound from supply spool 70and traverses coating zone 75 with the same spiral path as previouslydescribed, rewinding onto take-up spool 71. This embodiment illustratescollector device 72 for collecting excess material that would otherwisepass through the space between successive wraps of tape and couldpotentially contaminate other parts of the coater, as well as the backside of the tape. The collector consists of either an unwind/rewind pairof rollers (78/79) with standard web handling rollers for substrate 72,or an endless belt of film running between rollers 78/79. The substrate72, which could be a plastic film such as PET or other, accumulatesexcess material during the tape coating operation and may be readilydiscarded as the material buildup necessitates.

Yet another embodiment, shown in FIG. 83, shows a method by which bothsides of the substrate can be coated in a single pass. Here the web pathpasses over deposition zone 84, coating one side of the substrate, asshown in FIG. 79, then between feed roller 80 and receiving roller 82tape 83 may be twisted by 180 degrees about the tape axis along themachine direction. The web path continues into subsequent depositionzone 81, where the backside coating may be applied. Such dual-sidecoating may be of benefit for materials having both sides active(recordable or information-bearing), or requiring a vacuum backcoat forfriction and/or static control. With conventional coating methods, dualside coatings require either an additional coating pass or an additionalbackside coating station, both of which add production time and cost.

As can be seen in FIG. 84, optical storage media may take various formsas shown by alternative optical media forms 8400, each form offeringdiffering attributes of size, transfer speed, storage capacity, andcost. Alternative optical media forms 8400 include drum shaped opticalstorage media 8410 and 8420, flexible disk optical storage media 8430,compact reel-to-reel optical storage tape 8440, and optical storage card8450.

Drum shaped optical storage media 8410, 8420 may offer transfer ratesfrom approximately 6.5 MB/s to approximately 13.5 MB/s and storagecapacity from approximately 5.6 GB to approximately 102 GB.

Compact reel-to-reel tape 8440 shaped optical storage media (also knownas mini-optical tape) may offer transfer rates from approximately 3.2MB/s to approximately 6.7 MB/s and storage capacity from approximately255 GB to approximately 1130 GB.

Optical storage media may be selected from a set including alternativeoptical media form 8400 for a particular application such that thephysical size, and/or storage capacity, and/or transfer rate satisfiesrequirements of the application.

Optical flexible disk 8430, compact reel-to-reel 8440, and optical card8450 may be incorporated into a housing providing easy portability andprotection of the media, and may be appropriate for applications inwhich the media may be frequently handled by a user.

FIG. 85, a possible embodiment of an optical storage media system 8500includes an alternative optical media form 8400 loaded into an opticaldrive 8520 which fits into a typical DVD drive sized bay of a personalcomputer (PC) 8540. Alternative optical media form 8400 may beconstructed of a phase change optical media employing red, blue, or UVlaser with one or more pickup heads for recording to and reading fromalternative optical media form 8400. Other types of optical media suchas dye for WORM and magneto-optical for erasable optical media may alsobe suitable.

In this embodiment, optical drive 8520 communicates with PC 8540 harddrive 8530, using a portion of a predetermined size of hard drive 8540to improve random access to information on alternative optical mediaform 8400. It may be possible that alternative optical media form 8400,through optical drive 8520 offers a transfer rate that may be fasterthan disk drive 8530. This may be accomplished in various ways, with oneway being increasing the number of pickup heads in optical drive 8520used to record or read alternative optical media form 8400. An increasein pickup heads may directly enable faster data transfer rate to/fromalternative optical media form 8400.

When system 8500 may be used in an audio or video entertainmentapplication, there may be unique algorithms and formats applied to theportion of hard drive 8540 that allow users to rapidly access portionsof the information stored on alternative optical media form 8400. As anexample, the algorithms may allow a user to view thumbnails of moviescenes located a different physical locations on alternative opticalmedia form 8400, and then access a selected movie. These algorithms andformats may include index or location information of the moviesassociated with the thumbnails on alternative optical media form 8400,enabling fast access to the selected movie. Information stored on diskdrive 8530 may include tracking data that determines what informationmay be only on alternative optical media form 8400 and what has beentransferred to hard drive 8530. Other uses for system 8500 includearchive and backup of images, home movies, business information, orarchive library services.

Another possible embodiment of an optical storage system may be shown inFIG. 86. A stand-alone digital home entertainment system 8600 may besimilar in function to the possible embodiment of FIG. 85. System 8600may have a dedicated processor (not shown) communicating with allelements of system 8600, multimedia components (not shown), a built-inhard drive 8530, a USB interface 8640, or other communication port 8650.System 8600 further contains alternative optical media form 8400 andoptical drive 8520 of the embodiment of FIG. 85. System 8600 may furtherinclude other storage devices such as a DVD 8620. Each of the storageelements in system 8600 can communicate through communication channels8610 or 8630 or through the dedicated processor. It may be possible thatalternative optical media form 8400, through optical drive 8520 offers atransfer rate that may be faster than disk drive 8530.

System 8600 may connect to a PC via a wired or wireless LAN. It may alsoallow recording a plurality of programs using standard TV format andHDTV format onto alternative optical media form 8400. Using meanssimilar to the embodiment of FIG. 2, system 8600 uses a portion of harddrive 8530 to improve the speed of access to portions of the informationstored on alternative optical media form 8400, including thumbnails ofmovies. Information stored on disk drive 8530 may include tracking datathat determines what information may be only on alternative opticalmedia form 8400 and what has been transferred to hard drive 8530. Otheruses for system 8600 include archive and backup of images, home movies,business information, or archive library services.

System 8600A may also be used as an expandable storage Digital VideoRecorder (DVR). Since a DVR records video information to a hard drive,the storage capacity may be based on the capacity of the hard drive.Unwanted results such as users losing recorded programs, or recording ofnew shows being halted occur when the capacity of the hard drive limitmay be reached.

By including an alternative optical media form 8400 and optical drive8520 in an embodiment of system 8600 being used as a DVR, video storagemay be now augmented beyond the hard drive limit to include alternativeoptical media form 8400. In an embodiment of system 8600 wherein opticalstorage media may be removable, the amount of storage capacity of system8600 may be unlimited. Compact reel-to-reel 8440 optical storage mediamay be a possible embodiment of alternative optical media form 8400because of its high volumetric storage density.

FIG. 87 shows another possible embodiment using alternative opticalmedia form 8400 in system. Camera 8700 may incorporate a compactreel-to-reel 8440 embodiment of alternative optical media form 8400.Optical storage media may be removable. Because of the high volumetricstorage density of compact reel-to-reel 8440 optical storage media,video information may be stored in uncompressed format.

The format of information of each recording on alternative optical mediaform 8400 in this embodiment may be selected from a set including DVDand HDVD formats.

Optical storage media used in camera 8700 may be used interchangeablyfor recording or reading with any of the other system embodiment hereindisclosed. Embodiments of alternative optical media form 8400 that meetthe electrical, physical, and interface requirements of DVD media mayalso be used on standard PC or home entertainment equipment.

The elements depicted in flow charts and block diagrams throughout thefigures may imply logical boundaries between the elements. However,according to software or hardware engineering practices, the depictedelements and the functions thereof may be implemented as parts of amonolithic software structure, as standalone software modules, or asmodules that employ external routines, code, services, and so forth, orany combination of these, and all such implementations are within thescope of the present disclosure. Thus, while the foregoing drawings anddescription set forth functional aspects of the disclosed systems, noparticular arrangement of software for implementing these functionalaspects should be inferred from these descriptions unless explicitlystated or otherwise required by the context.

Similarly, it will be appreciated that the various steps identified anddescribed above may be varied, and that the order of steps may beadapted to particular applications of the techniques disclosed herein.All such variations and modifications are intended to fall within thescope of this disclosure. As such, the depiction and/or description ofan order for various steps should not be understood to require aparticular order of execution for those steps, unless required by aparticular application, or explicitly stated or otherwise clear from thecontext.

The methods or processes described above, and steps thereof, may berealized in hardware, software, or any combination of these suitable fora particular application. The hardware may include a general-purposecomputer and/or dedicated computing device. The processes may berealized in one or more microprocessors, microcontrollers, embeddedmicrocontrollers, programmable digital signal processors or otherprogrammable device, along with internal and/or external memory. Theprocesses may also, or instead, be embodied in an application specificintegrated circuit, a programmable gate array, programmable array logic,or any other device or combination of devices that may be configured toprocess electronic signals. It will further be appreciated that one ormore of the processes may be realized as computer executable codecreated using a structured programming language such as C, an objectoriented programming language such as C++, or any other high-level orlow-level programming language (including assembly languages, hardwaredescription languages, and database programming languages andtechnologies) that may be stored, compiled or interpreted to run on oneof the above devices, as well as heterogeneous combinations ofprocessors, processor architectures, or combinations of differenthardware and software.

Thus, in one aspect, each method described above and combinationsthereof may be embodied in computer executable code that, when executingon one or more computing devices, performs the steps thereof. In anotheraspect, the methods may be embodied in systems that perform the stepsthereof, and may be distributed across devices in a number of ways, orall of the functionality may be integrated into a dedicated, standalonedevice or other hardware. In another aspect, means for performing thesteps associated with the processes described above may include any ofthe hardware and/or software described above. All such permutations andcombinations are intended to fall within the scope of the presentdisclosure.

While embodiments of the invention has been disclosed in connection withcertain possible embodiments, other embodiments would be understood byone of ordinary skill in the art and are encompassed herein.

1. A data storage system comprising: an optical media having a defectand a plurality of tracks on each side of the defect exhibiting (i)fields of modulated wobble indicative of defect location informationnext to the defect and (ii) fields of modulated wobble indicative ofdata; an optical pick-up unit configured to read the fields of modulatedwobble; and at least one controller operatively arranged with thepick-up unit and configured to, in response to the pick-up unitdetecting defect location information on one side of the defect, commandmovement of the media in a first direction such that the pick-up unit ispositioned adjacent to the fields of modulated wobble indicative of dataon the other side of the defect.
 2. The system of claim 1 wherein the atleast one controller is further configured to command the pick-up unitto refocus on the fields of modulated wobble indicative of data on theother side of the defect.
 3. The system of claim 2 wherein, afterrefocusing, the at least one controller is further configured to commandmovement of the media in a second direction opposite the first such thatthe defect approaches the pick-up unit.
 4. The system of claim 3 whereinthe at least one controller commands movement of the media in the seconddirection until the pick-up unit detects defect location information orthe pick-up unit loses focus.
 5. The system of claim 4 wherein the atleast one controller is further configured to record a position of thepick-up unit if the pick-up unit detects defect location information. 6.The system of claim 4 wherein the at least one controller is furtherconfigured to record a time during which movement is commanded in thesecond direction.
 7. The system of claim 4 wherein the at least onecontroller is further configured to identify the media as defective ifthe pick-up unit loses focus and the pick-up unit cannot be refocused.8. The system of claim 4 wherein the at least one controller is furtherconfigured to command movement of the media in the first direction for apredetermined period of time.
 9. A method for calibrating a data storagesystem including (i) an optical pick-up unit and (ii) an optical mediahaving a defect and a plurality of tracks on each side of the defect,the plurality of tracks exhibiting fields of modulated wobble indicativeof defect location information next to the defect and exhibiting fieldsof modulated wobble indicative of data, the method comprising: readingthe fields of modulated wobble; detecting defect location information onone side of the defect; and positioning the media such that the pick-upunit is adjacent to the fields of modulated wobble indicative of data onthe other side of the defect in response to detecting the defectlocation information on the one side of the defect.
 10. The method ofclaim 9 further comprising commanding the pick-up unit to refocus on thefields of modulated wobble indicative of data on the other side of thedefect.
 11. The method of claim 10 further comprising commandingmovement of the media such that the defect approaches the pick-up unit.12. The method of claim 11 wherein movement of the media is commandeduntil the pick-up unit detects defect location information or thepick-up unit loses focus.
 13. The method of claim 12 further comprisingrecording a position of the pick-up unit if the pick-up unit detectsdefect location information.
 14. The method of claim 12 furthercomprising identifying the media as defective if the pick-up unit losesfocus and the pick-up unit cannot be refocused.
 15. A data storagesystem comprising: an optical media having a defect and a plurality oftracks on each side of the defect exhibiting (i) fields of modulatedwobble indicative of defect location information next to the defect and(ii) fields of modulated wobble indicative of data; an optical pick-upunit configured to read the fields of modulated wobble; and at least onecontroller operatively arranged with the pick-up unit and configured to,in response to the pick-up unit detecting defect location information onone side of the defect, command movement of the media in a firstdirection such that the pick-up unit is positioned adjacent to thefields of modulated wobble indicative of data on the other side of thedefect, command the pick-up unit to refocus on the fields of modulatedwobble indicative of data on the other side of the defect, and commandmovement of the media in a second direction opposite the first such thatthe defect approaches the pick-up unit until the pick-up unit detectsdefect location information or the pick-up unit loses focus.
 16. Thesystem of claim 15 wherein the at least one controller is furtherconfigured to record a position of the pick-up unit if the pick-up unitdetects defect location information.
 17. The system of claim 15 whereinthe at least one controller is further configured to record a timeduring which movement is commanded in the second direction.
 18. Thesystem of claim 15 wherein the at least one controller is furtherconfigured to identify the media as defective if the pick-up unit losesfocus and the pick-up unit cannot be refocused.
 19. The system of claim15 wherein the at least one controller is further configured to commandmovement of the media in the first direction for a predetermined periodof time.